I possess a first edition Proceed GT 12/500, which I thoroughly enjoy modifying and driving; nonetheless, I have encountered this issue since the day of purchase. The stock exhaust of the GT includes a primary catted downpipe positioned post-turbo and an additional one located immediately thereafter (which I purchased without). During a test drive, I detected an odour during heavy acceleration with the windows down, but I dismissed it. Fast forward one to two years of ownership, I resolved to enhance power and sound by constructing a custom catless downpipe. Following the installation of the downpipe and subsequent tuning, the exhaust fumes are incessant and overwhelming when the windows are lowered. Even with the windows closed, I perceive that they still infiltrate the cabin. Nonetheless, I am uncertain about the issue, given the odour was present prior to my removal of the catalytic converter. I attempted to extend the tailpipes, but there was no alteration.
Do you have any recommendations?