Modern Vespa

My bike is making a loud noise while the engine is running. It sounds like an exhaust leak. Does the 2018 GTS use the graphite bushing or does it just have a gasket in the head?

Should have both, unless you have an aftermarket exhaust. I'd also check to see if you manifold is cracked, which can happen with an aftermarket pipe.

It's all stock. About 4300 miles on it but most are highway miles, like interstate around 75 to 80 mph or state and county highway topping out at around 65 to 70 mph.

When I was looking at Scooterwest and Scooterpartsco parts lists the bikes with the graphite bushing were earlier model bikes which is why I'm confused. It's a good 3 to 400 miles to a shop plus some shops will not look at your bike right away if you bought it from a different dealer.

It's nighttime right now or I'd just go outside and look at the exhaust.

A 2018 with stock does have a graphite bushing. Yes it's probably screwed based on your earlier description.

My 2014 eats those midpipe graphite exhaust gaskets..
One every 1500 or so miles.

I keep one in my tool bag, and can change one in 15 minutes on the road... after the pipe cools down.

Ouch - I'm pretty sure mine last 3 or 4 times that. Is there something off with your pipe connection (like rust grinding down the bushing, or deformed pipe preventing good seal)? Or maybe the clamp is no good?

Get it fixed ASAP. A tiny pinhole leak in the 2018 exhaust melted my wiring harness during the 2021 Scooter Cannonball. Caused my one one only DNF.

t's a graphite bushing. All the OEM Piaggio pipes for the GTs and GTV use one. Scooterpartsco is in Fayetteville, AR. Where are you located?

I'm in Blytheville. North of Memphis about 60 miles.

Just found a missing or broken stud also.

A colleague of mine has the same issue with his GTS 300, not every 1500 miles but more like every 3000 miles.
He thinks the problem is that the exhaust manifold is too short, therefore too close to the engine and gets too hot.

I have a BV 300 with the same engine. But in a BV the manifold is much longer.
So far after 30000km no issues with the bushing.

Except the Euro 5 and 2023

It uses a graphite bushing. If it is making a noise you will find that the bushing has probably been chewed down and only the mesh has been left behind.
It is an easy fix, provided things go smoothly.
You can start by putting some penetrating liquid (even WD40) the night before on the exhaust clamp nut and threads.
The next day you start by loosening the exhaust clamp, generally it is a 17mm socket or wrench/spanner, then undo the 3 bolt that hold up the exhaust and wiggle the exhaust off.
You will find that the bushing has been worn off and you should be able to get it out with a screw driver.
Now you will need to expand the exhaust opening to put the new bushing in.They sell exhaust pipe expanders at Harbor freight.
You can get the OEM bushing from Scooterparts.com or Scooterwest, Id get a few and keep them.
Once the pipe has been expanded, you can fit the bushing in and it generally will go in one way if it is OEM. The yamaha ones can go in either way.
I doubt your manifold is busted.
Just take a wire brush and clean the exhaust before you put it back on.
There are a few youtube videos of doing this job. Robot has one I know.
Good luck with it, not worth riding till it is fixed cuz you can melt brake lines etc..