I have a 2wd cossie with 3" Mongoose, KN, Montune Chip, Turbonetics T34 ar.48, grey injectors, low compression pistons, and ported top (???). Had it on a rolling road and the results were 350bhp@6100 rpm., and 417nm@4400rpm. 1,6 bar.

Will a ar63 exhausthouse be a good upgrade, or won't it make any differance?