Modern Vespa

I ordered vespa sport exhaust (part number 1A020151) for GTS300 in which the official vespa web said it is compatible with the new GTV300 2023, when I tried to install it, apparently it does fit to the header

Anyone can help me solve this problem?
Is there any part I should change using which model engine for the header?

Thanks

That exhaust is for the E5.
Your scoot is E4 (that's clearly an e3/4 header in your pic).

To make that exhaust fit you'd need to buy an E5 header

Do you mind help me, which part number should I buy?

honestly I don't think you should try. The E5 header has an extra catalytic in it and I think the E5 ecu has a different mapping. So sticking an E5 header on yours would be a mismatch.

However this exhaust is actually homologated made by arrow for vespa, I took a sneak peek into the hole inlet I saw there is a catalytic converter inside the beginning of the muffler, so the mapping would still match I guess, if I can use the long header then perhaps I can detach the cat inside it coz the mufffler has catalytic inside, what do you think?

I recommend not using it at all.

Buy an exhaust designed for an E4 HPE GTS.


Note: In Asia Pacific we don't get the E5 of either the GTS or GTV.

I don't have experience changing an E4 to E5, but you would need to buy an E5 Header Manifold as a place to start as others have stated too. (Link Below)
You may need to change your Lambda Sensor too.
You might consider talking to your Local Vespa Dealer as there might be some other engine settings that need to be addressed, or it could connect and run great ... good luck.

https://www.sip-scootershop.com/en/product/exhaust-manifold-piaggio_PI017571