I just did my top hats today.The noise mine was doing is when the car was in park i would turn the wheel from all the way left to all the way right and a binding noise would come out off the defective top hat.
Biggest gain I notice on the but dyno is when boost is at zero on take off the car feels less laggy. Feels more like a n/a car. Nothing crazy but it helps. I’m only running a 20 g right now but whit a bigger you would probably see more gain.
The bling factor is a nice touch as I hated the plastic manifold.
Turbo parts Canada does offer the service of installing a bigger wastegate flapper for 150$ or 200$. The problem is when i got there to get the job done,is machine shop was down for 3 week. I ended up buying a 20 g instead.