as far as i no, not alot of ppl modify the twin cam to any major extent... im not saying that ppl havnt done it but it doesnt respond aswell to modificatios as other engines that could be used ie the pinto. i no this doesn realy help what u wanna do but i thought i would say incase u thought ppl were being disinerested etc. might be worth going on some siera owners club forums as u might have abit more luck

good luck and let us no if u find anything out




also u dont say weather it is the carbed or the injection version of the engine, as if it is the carbed engine then it will be harder to do than the injected engine

hth