gas flowed down pipe
 

hi, could anybody tell me what difference a larger diameter group n gas flowed downpipe from turbo would make?
thanks

anybody?

On what car?
A decat downpipe will add power to your car if it has a cat on the existing D/P.
What diameter are you asking about?
a Gp N D/P will not necessarily be the best performance mod depending on your current spec and aspirations.