diff --git a/packages/api-kit/src/SafeApiKit.ts b/packages/api-kit/src/SafeApiKit.ts
index 0623228c8..01ac92f1d 100644
--- a/packages/api-kit/src/SafeApiKit.ts
+++ b/packages/api-kit/src/SafeApiKit.ts
@@ -831,6 +831,10 @@ class SafeApiKit {
       throw new Error('Signature must not be empty')
     }
 
+    // We are receiving the timestamp in seconds (block timestamp), but the API expects it in milliseconds
+    const getISOString = (date: number | undefined) =>
+      !date ? null : new Date(date * 1000).toISOString()
+
     return sendRequest({
       url: `${this.#txServiceBaseUrl}/v1/safes/${safeAddress}/safe-operations/`,
       method: HttpMethod.Post,
@@ -847,8 +851,8 @@ class SafeApiKit {
           ? null
           : userOperation.paymasterAndData,
         entryPoint,
-        validAfter: !options?.validAfter ? null : options?.validAfter,
-        validUntil: !options?.validUntil ? null : options?.validUntil,
+        validAfter: getISOString(options?.validAfter),
+        validUntil: getISOString(options?.validUntil),
         signature: userOperation.signature,
         moduleAddress
       }
diff --git a/packages/api-kit/tests/endpoint/index.test.ts b/packages/api-kit/tests/endpoint/index.test.ts
index 68f96c9a3..18dfd2fe1 100644
--- a/packages/api-kit/tests/endpoint/index.test.ts
+++ b/packages/api-kit/tests/endpoint/index.test.ts
@@ -683,7 +683,13 @@ describe('Endpoint tests', () => {
       }
 
       const entryPoint = '0x5FF137D4b0FDCD49DcA30c7CF57E578a026d2789'
-      const options = { validAfter: 123, validUntil: 234 }
+
+      const ethersProvider = protocolKit.getSafeProvider().getExternalProvider()
+      const timestamp = (await ethersProvider.getBlock('latest'))?.timestamp || 0
+
+      const validAfter = timestamp - 60_000
+      const validUntil = timestamp + 60_000
+      const options = { validAfter, validUntil }
 
       await chai
         .expect(
@@ -711,7 +717,8 @@ describe('Endpoint tests', () => {
           maxPriorityFeePerGas: userOperation.maxPriorityFeePerGas.toString(),
           paymasterAndData: userOperation.paymasterAndData,
           entryPoint,
-          ...options,
+          validAfter: new Date(validAfter * 1000).toISOString(),
+          validUntil: new Date(validUntil * 1000).toISOString(),
           signature: userOperation.signature,
           moduleAddress
         }
diff --git a/packages/relay-kit/src/packs/safe-4337/Safe4337Pack.test.ts b/packages/relay-kit/src/packs/safe-4337/Safe4337Pack.test.ts
index e24a5c761..390e41bcc 100644
--- a/packages/relay-kit/src/packs/safe-4337/Safe4337Pack.test.ts
+++ b/packages/relay-kit/src/packs/safe-4337/Safe4337Pack.test.ts
@@ -367,7 +367,7 @@ describe('Safe4337Pack', () => {
         maxFeePerGas: 100000n,
         maxPriorityFeePerGas: 200000n,
         verificationGasLimit: 150000n,
-        preVerificationGas: 100000n
+        preVerificationGas: 105000n
       })
     })
 
@@ -395,7 +395,7 @@ describe('Safe4337Pack', () => {
         maxFeePerGas: 100000n,
         maxPriorityFeePerGas: 200000n,
         verificationGasLimit: 150000n,
-        preVerificationGas: 100000n
+        preVerificationGas: 105000n
       })
     })
 
@@ -454,7 +454,7 @@ describe('Safe4337Pack', () => {
         maxFeePerGas: 100000n,
         maxPriorityFeePerGas: 200000n,
         verificationGasLimit: 150000n,
-        preVerificationGas: 100000n
+        preVerificationGas: 105000n
       })
     })
 
@@ -529,7 +529,7 @@ describe('Safe4337Pack', () => {
         maxFeePerGas: 100000n,
         maxPriorityFeePerGas: 200000n,
         verificationGasLimit: 150000n,
-        preVerificationGas: 100000n
+        preVerificationGas: 105000n
       })
     })
   })
@@ -557,7 +557,7 @@ describe('Safe4337Pack', () => {
         fixtures.OWNER_1.toLowerCase(),
         new protocolKit.EthSafeSignature(
           fixtures.OWNER_1,
-          '0x63de7fdf99bcf20a1981ae74c3960604139d8bf025da894abc11604b30f438e82ceb0d37e73bf16b0b8b896f8be82a49750433733c0414fe4a3b8182a3875e1f1c',
+          '0x8ce4849928aef19e8f5cc199e069a451568dcbaca194a86dc953ae24acac3cbb02a458343127b2a52e1af3b99622b2fc8f1bd9957f84828c33940532a94ea3261c',
           false
         )
       )
diff --git a/packages/relay-kit/src/packs/safe-4337/Safe4337Pack.ts b/packages/relay-kit/src/packs/safe-4337/Safe4337Pack.ts
index 106830bdb..d86926b64 100644
--- a/packages/relay-kit/src/packs/safe-4337/Safe4337Pack.ts
+++ b/packages/relay-kit/src/packs/safe-4337/Safe4337Pack.ts
@@ -478,15 +478,17 @@ export class Safe4337Pack extends RelayKitBasePack<{
         preVerificationGas: BigInt(userOperation?.preVerificationGas || 0),
         maxFeePerGas: BigInt(userOperation?.maxFeePerGas || 0),
         maxPriorityFeePerGas: BigInt(userOperation?.maxPriorityFeePerGas || 0),
-        paymasterAndData: userOperation?.paymasterData || '0x',
-        signature: userOperation?.signature || '0x'
+        paymasterAndData: ethers.hexlify(
+          ethers.concat([userOperation?.paymaster || '0x', userOperation?.paymasterData || '0x'])
+        ),
+        signature: safeOperationResponse.preparedSignature || '0x'
       },
       {
         chainId: this.#chainId,
         moduleAddress: this.#SAFE_4337_MODULE_ADDRESS,
         entryPoint: userOperation?.entryPoint || this.#ENTRYPOINT_ADDRESS,
-        validAfter: validAfter ? new Date(validAfter).getTime() : undefined,
-        validUntil: validUntil ? new Date(validUntil).getTime() : undefined
+        validAfter: this.#timestamp(validAfter),
+        validUntil: this.#timestamp(validUntil)
       }
     )
 
@@ -499,6 +501,15 @@ export class Safe4337Pack extends RelayKitBasePack<{
     return safeOperation
   }
 
+  /**
+   *
+   * @param date An ISO string date
+   * @returns The timestamp in seconds to send to the bundler
+   */
+  #timestamp(date: string | null) {
+    return date ? new Date(date).getTime() / 1000 : undefined
+  }
+
   /**
    * Signs a safe operation.
    *
@@ -546,7 +557,7 @@ export class Safe4337Pack extends RelayKitBasePack<{
         this.#SAFE_4337_MODULE_ADDRESS
       )
     } else {
-      const safeOpHash = await safeOp.getHash()
+      const safeOpHash = safeOp.getHash()
 
       signature = await this.protocolKit.signHash(safeOpHash)
     }
diff --git a/packages/relay-kit/src/packs/safe-4337/estimators/PimlicoFeeEstimator.ts b/packages/relay-kit/src/packs/safe-4337/estimators/PimlicoFeeEstimator.ts
index f00932f43..0830929ca 100644
--- a/packages/relay-kit/src/packs/safe-4337/estimators/PimlicoFeeEstimator.ts
+++ b/packages/relay-kit/src/packs/safe-4337/estimators/PimlicoFeeEstimator.ts
@@ -22,7 +22,8 @@ export class PimlicoFeeEstimator implements IFeeEstimator {
     return {
       callGasLimit: userOperation.callGasLimit + userOperation.callGasLimit / 2n,
       verificationGasLimit:
-        userOperation.verificationGasLimit + userOperation.verificationGasLimit / 2n
+        userOperation.verificationGasLimit + userOperation.verificationGasLimit / 2n,
+      preVerificationGas: userOperation.preVerificationGas + userOperation.preVerificationGas / 20n
     }
   }
 
diff --git a/packages/safe-kit/src/extensions/safe-operations/SafeOperationClient.ts b/packages/safe-kit/src/extensions/safe-operations/SafeOperationClient.ts
index 3be2a69a6..e93e87a16 100644
--- a/packages/safe-kit/src/extensions/safe-operations/SafeOperationClient.ts
+++ b/packages/safe-kit/src/extensions/safe-operations/SafeOperationClient.ts
@@ -45,19 +45,7 @@ export class SafeOperationClient {
     safeOperation = await this.safe4337Pack.signSafeOperation(safeOperation)
 
     if (isMultisigSafe) {
-      const userOperation = safeOperation.toUserOperation()
-      userOperation.signature = safeOperation.encodedSignatures() // Without validity dates
-
-      await this.apiKit.addSafeOperation({
-        entryPoint: safeOperation.data.entryPoint,
-        moduleAddress: safeOperation.moduleAddress,
-        safeAddress: safeOperation.data.safe,
-        userOperation,
-        options: {
-          validAfter: safeOperation.data.validAfter,
-          validUntil: safeOperation.data.validUntil
-        }
-      })
+      await this.apiKit.addSafeOperation(safeOperation)
 
       const safeOperationHash = safeOperation.getHash()
 
diff --git a/playground/relay-kit/api-kit-interoperability.ts b/playground/relay-kit/api-kit-interoperability.ts
index 66c2041de..2745fdb0e 100644
--- a/playground/relay-kit/api-kit-interoperability.ts
+++ b/playground/relay-kit/api-kit-interoperability.ts
@@ -10,7 +10,7 @@ const SAFE_ADDRESS = '' // Safe 2/N
 const CHAIN_NAME = 'sepolia'
 
 // Constants
-const BUNDLER_URL = `https://api.pimlico.io/v1/${CHAIN_NAME}/rpc?apikey=${PIMLICO_API_KEY}`
+const BUNDLER_URL = `https://api.pimlico.io/v2/${CHAIN_NAME}/rpc?apikey=${PIMLICO_API_KEY}`
 const PAYMASTER_URL = `https://api.pimlico.io/v2/${CHAIN_NAME}/rpc?apikey=${PIMLICO_API_KEY}`
 const RPC_URL = 'https://sepolia.gateway.tenderly.co'
 const PAYMASTER_ADDRESS = '0x0000000000325602a77416A16136FDafd04b299f' // SEPOLIA
diff --git a/playground/relay-kit/usdc-transfer-4337-counterfactual.ts b/playground/relay-kit/usdc-transfer-4337-counterfactual.ts
index 7b3e91d88..50ac4795f 100644
--- a/playground/relay-kit/usdc-transfer-4337-counterfactual.ts
+++ b/playground/relay-kit/usdc-transfer-4337-counterfactual.ts
@@ -19,7 +19,7 @@ const CHAIN_NAME = 'sepolia'
 // const CHAIN_NAME = 'gnosis'
 
 // Bundler URL
-const BUNDLER_URL = `https://api.pimlico.io/v1/${CHAIN_NAME}/rpc?apikey=${PIMLICO_API_KEY}` // PIMLICO
+const BUNDLER_URL = `https://api.pimlico.io/v2/${CHAIN_NAME}/rpc?apikey=${PIMLICO_API_KEY}` // PIMLICO
 
 // USDC CONTRACT ADDRESS IN SEPOLIA
 // faucet: https://faucet.circle.com/
diff --git a/playground/relay-kit/usdc-transfer-4337-erc20-counterfactual.ts b/playground/relay-kit/usdc-transfer-4337-erc20-counterfactual.ts
index f80a23db9..dbfad9543 100644
--- a/playground/relay-kit/usdc-transfer-4337-erc20-counterfactual.ts
+++ b/playground/relay-kit/usdc-transfer-4337-erc20-counterfactual.ts
@@ -18,7 +18,7 @@ const RPC_URL = 'https://sepolia.gateway.tenderly.co' // SEPOLIA
 // const RPC_URL = 'https://rpc.gnosischain.com/' // GNOSIS
 
 // Bundler URL
-const BUNDLER_URL = `https://api.pimlico.io/v1/${CHAIN_NAME}/rpc?apikey=${PIMLICO_API_KEY}` // PIMLICO
+const BUNDLER_URL = `https://api.pimlico.io/v2/${CHAIN_NAME}/rpc?apikey=${PIMLICO_API_KEY}` // PIMLICO
 
 // PAYMASTER ADDRESS
 const paymasterAddress = '0x0000000000325602a77416A16136FDafd04b299f' // SEPOLIA
diff --git a/playground/relay-kit/usdc-transfer-4337-erc20.ts b/playground/relay-kit/usdc-transfer-4337-erc20.ts
index 3dd524274..770057245 100644
--- a/playground/relay-kit/usdc-transfer-4337-erc20.ts
+++ b/playground/relay-kit/usdc-transfer-4337-erc20.ts
@@ -18,7 +18,7 @@ const RPC_URL = 'https://sepolia.gateway.tenderly.co' // SEPOLIA
 // const RPC_URL = 'https://rpc.gnosischain.com/' // GNOSIS
 
 // Bundler URL
-const BUNDLER_URL = `https://api.pimlico.io/v1/${CHAIN_NAME}/rpc?apikey=${PIMLICO_API_KEY}` // PIMLICO
+const BUNDLER_URL = `https://api.pimlico.io/v2/${CHAIN_NAME}/rpc?apikey=${PIMLICO_API_KEY}` // PIMLICO
 
 // PAYMASTER ADDRESS
 const paymasterAddress = '0x0000000000325602a77416A16136FDafd04b299f' // SEPOLIA
diff --git a/playground/relay-kit/usdc-transfer-4337-sponsored-counterfactual.ts b/playground/relay-kit/usdc-transfer-4337-sponsored-counterfactual.ts
index 2e89c7b5a..7697558bc 100644
--- a/playground/relay-kit/usdc-transfer-4337-sponsored-counterfactual.ts
+++ b/playground/relay-kit/usdc-transfer-4337-sponsored-counterfactual.ts
@@ -21,7 +21,7 @@ const RPC_URL = 'https://sepolia.gateway.tenderly.co' // SEPOLIA
 // const RPC_URL = 'https://rpc.gnosischain.com/' // GNOSIS
 
 // Bundler URL
-const BUNDLER_URL = `https://api.pimlico.io/v1/${CHAIN_NAME}/rpc?apikey=${PIMLICO_API_KEY}` // PIMLICO
+const BUNDLER_URL = `https://api.pimlico.io/v2/${CHAIN_NAME}/rpc?apikey=${PIMLICO_API_KEY}` // PIMLICO
 
 // Paymaster URL
 const PAYMASTER_URL = `https://api.pimlico.io/v2/${CHAIN_NAME}/rpc?apikey=${PIMLICO_API_KEY}` // PIMLICO
diff --git a/playground/relay-kit/usdc-transfer-4337-sponsored.ts b/playground/relay-kit/usdc-transfer-4337-sponsored.ts
index 7751c0c91..a3aebbb7e 100644
--- a/playground/relay-kit/usdc-transfer-4337-sponsored.ts
+++ b/playground/relay-kit/usdc-transfer-4337-sponsored.ts
@@ -21,7 +21,7 @@ const RPC_URL = 'https://sepolia.gateway.tenderly.co' // SEPOLIA
 // const RPC_URL = 'https://rpc.gnosischain.com/' // GNOSIS
 
 // Bundler URL
-const BUNDLER_URL = `https://api.pimlico.io/v1/${CHAIN_NAME}/rpc?apikey=${PIMLICO_API_KEY}` // PIMLICO
+const BUNDLER_URL = `https://api.pimlico.io/v2/${CHAIN_NAME}/rpc?apikey=${PIMLICO_API_KEY}` // PIMLICO
 
 // Paymaster URL
 const PAYMASTER_URL = `https://api.pimlico.io/v2/${CHAIN_NAME}/rpc?apikey=${PIMLICO_API_KEY}` // PIMLICO
diff --git a/playground/relay-kit/usdc-transfer-4337.ts b/playground/relay-kit/usdc-transfer-4337.ts
index b58105444..ded38476c 100644
--- a/playground/relay-kit/usdc-transfer-4337.ts
+++ b/playground/relay-kit/usdc-transfer-4337.ts
@@ -10,7 +10,7 @@ const PIMLICO_API_KEY = ''
 const SAFE_ADDRESS = ''
 
 // Bundler URL
-const BUNDLER_URL = `https://api.pimlico.io/v1/sepolia/rpc?apikey=${PIMLICO_API_KEY}` // PIMLICO
+const BUNDLER_URL = `https://api.pimlico.io/v2/sepolia/rpc?apikey=${PIMLICO_API_KEY}` // PIMLICO
 
 // RPC URL
 const RPC_URL = 'https://sepolia.gateway.tenderly.co'
diff --git a/playground/safe-kit/send-safe-operation.ts b/playground/safe-kit/send-safe-operation.ts
index 8e21ca5d9..45b6a6fe8 100644
--- a/playground/safe-kit/send-safe-operation.ts
+++ b/playground/safe-kit/send-safe-operation.ts
@@ -1,3 +1,4 @@
+import { ethers } from 'ethers'
 import { SafeClientResult, createSafeClient, safeOperations } from '@safe-global/safe-kit'
 import { generateTransferCallData } from '../utils'
 
@@ -20,9 +21,9 @@ const usdcAmount = 10_000n // 0.01 USDC
 const paymasterAddress = '0x0000000000325602a77416A16136FDafd04b299f' // SEPOLIA
 
 // Paymaster URL
-const PIMLICO_API_KEY = '30b296fa-8947-4775-b44a-b225336e2a66'
+const PIMLICO_API_KEY = ''
 const PAYMASTER_URL = `https://api.pimlico.io/v2/sepolia/rpc?apikey=${PIMLICO_API_KEY}` // PIMLICO
-const BUNDLER_URL = `https://api.pimlico.io/v1/sepolia/rpc?apikey=${PIMLICO_API_KEY}`
+const BUNDLER_URL = `https://api.pimlico.io/v2/sepolia/rpc?apikey=${PIMLICO_API_KEY}`
 
 async function send(): Promise<SafeClientResult> {
   const safeClient = await createSafeClient({
@@ -59,7 +60,16 @@ async function send(): Promise<SafeClientResult> {
   }
   const transactions = [transferUSDC, transferUSDC]
 
-  const safeOperationResult = await safeClientWithSafeOperation.sendSafeOperation({ transactions })
+  const ethersProvider = new ethers.JsonRpcProvider(RPC_URL)
+  const timestamp = (await ethersProvider.getBlock('latest'))?.timestamp || 0
+
+  const safeOperationResult = await safeClientWithSafeOperation.sendSafeOperation({
+    transactions,
+    options: {
+      validAfter: timestamp - 60_000,
+      validUntil: timestamp + 60_000
+    }
+  })
 
   console.log('-Send result: ', safeOperationResult)
 
@@ -73,7 +83,7 @@ async function confirm(safeClientResult: SafeClientResult, pk: string) {
 
   const safeClient = await createSafeClient({
     provider: RPC_URL,
-    signer: OWNER_1_PRIVATE_KEY,
+    signer: pk,
     safeOptions: {
       owners: [OWNER_1_ADDRESS, OWNER_2_ADDRESS, OWNER_3_ADDRESS],
       threshold: THRESHOLD,