Good advice, thanks. The engine is not rebuilt, but well maintained by a single owner before I purchased it. I dont really race the car in actual races, I just like opening up the secondarys on the 750 cfm carb and let it roar through the gears.I've recently modified the dual exauast to a more straight design, I was able to remove five feet, and four bends on both sides. I can feel a huge diffrence in the acceleration, also the tone is much deeper now. The most difficult part was modifing the exaust hangers. 72 caprice BB