Hah, sorry I didn't read your wanting to keep it NA comment on the first post. The rest of my post still stands though. Exhaust/Headers don't do much with this engine its about +/- 3HP from the dynos I have seen. Have to improve the engine and transmission and diff to get those speeds. If you are really up for it and have a knack for engines, or an experienced mechanic you have the option of boring out your L28 to 3.1L. Kits are sold from various places. Arizona Z Car / Motorsport Auto. I believe they run you around $3,200. Of course if you can located all the parts yourself be it junkyards or aftermarket, It should run you way less around $1300. And yeah of course if you just got the car, Change all the fluids, Check the sparks and such to give the car a tuneup if needed. Switch out those Park bench bumpers for early style ones or FRP. Anywho its your car and your choices! Do what you want and have a good time doing it =).