My 01' motor had some of the highest HP readings I have seen for the mods I had and it's mostly the common bolt on's, except for head work.
This got me 467HP and 508TQ - 11.3 1/4 mile @125MPH on Drag Radials:
SVS Headers, highest flowing headers made in my opinion. It's a "race only" header from what my research has shown... This is where I got all my power I think. Notice the equil length headers and perfect 5 into 1 collector... this is where these headers domintate in my opinion.
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http://www.mitchellmotorsport.co.nz/...er_Headers.jpg[/img]
NO CATS.... NO REAR EXHAUST = LOUD! (also big power gains from no cats...)
Side Borla exhaust
Smoothe tubes / K&N drop in's
Alum flywheel
SCT Tune
...can't think nof anything else power related to get the power I did.
I installed rockers and axctually lost power... Down to about 457HP, but again... this was another day on the Dyno, so who knows if the temp / weather conditions played a role. This may have also been because the rockers are not useful without headwork, then they will add power. I still managed an 11.6 at the track with the rockers, but I was also on a harder tire... and had alot of tire spin compared to my softer drag radials (BFG G-Force DR), so that is where I think I lost the .3 tents from at the drag strip... from a harder tire (Nitto 555).