Tomei UEL leak?
 

I have a what sounds like an exhaust leak but not from the header it sounds like maybe the overpipe. I know this is common for some of the cheaper headers but I wouldn't consider Tomei a cheap one. Is it normal to sound like that? I have double checked and made sure all bolts are tight. It doesn't always sound like it just at around 3k-5k at WOT.

get under your car and feel around to see if you can feel any air rushing out of the connections. however, I think it's just the noise that comes with the UEL and you don't have a leak. my Gruppe-S (almost identical to Tomei) has the same sounds of a leak but there really isn't any. you can hear it on a cold start pretty well but I have verified that there's no leaks.

Thinner side walls in aftermarket headers. Normal. /thread

This has been covered many times before and its normal so dont worry about it and go enjoy your car :cheers:

IMO best way to check for leaks is to drive 1k miles, get under the car and look for lots of black soot near all mating connections in the exhaust flow. Leaks can be very subtle such that you can't really tell there's air moving, but over time if there is one eventually you'll see soot buildup.

Here's an example of what to look for: https://www.google.com/search?q=soot...-F-04qjQc_M%3A

When I installed my header I took cell phone pics of all the major connections (block to header, collector to over pipe) and inspected after 1k miles using the original pic as a comparison.

Additionally if you're still using the stock tune, the VVT tables will not be optimized for the header and it will sound like crap.

Yea still running the stock tune it just sounds raspy and only at higher RPMs. OFT coming in soon maybe that will help