I'll tell whats overkill Deff...is that TB. Some guys with blower setups dont even use a TB that big...your MAF tables have got to be all over the place especially if it is just a canned ZZP Tune. Get a custom tune...with ER Rockers or a Cam and a Ported L36 TB or even a L67 TB...but ya...N* no WAY. THEN...get the headers...are you saying though with all your mods you NO exhaust work? That GT has to have as much knock as a 3.4" pulley on a bone stock GTP.
Edited for a thought...isn't your car Drive BY Wire electronic TB? How are you running a TB Spacer, N*, and had the U-Bend Deleted?
