The only "true" 4" turbo back exhaust starts with something like an HX40 or an S300 turbo. Anything else coming off an H1C and the like immediately necks down to 3.25" or whatever the turbo outlet measures. Kinda dumb, really.And it's "the" only true 4in turbo back.
The Stan's system doesn't have that problem.say you may have to cut a little out of your auto transmission cooler bracket to clear it