Somehow I had a spark plug blow out (stripped threads) so now I have to either have a thread insert put in or replace the heads. I'm leaning toward new heads since the cost of the new heads would probably ofset a lot of the labor involved in fixing the one (not crazy about an insert anyway). The question is, that since the heads are coming off, what else should i have modded/upgraded/replaced? My primary concerns are biggest bang for the buck, cost, and replacement of parts that are worn and would increase the life of the engine. I am not a drag racer, but I sometimes to a track day. I usually drive spirited, but I'm not looking to have the most horsepower out there so no turbo or sc. Things I have thought about are: rods, lifters, springs, rocker arms, manifold, throttle body, injectors, cam, and pully.

Page 2... I think my clutch is going too. Stiff pedal and engagement point has gotten pretty low. If I decide to do the clutch now, then that also opens up some possible mods such as tunnel plate, headers, exhaust. Should I go ahead and replace the master and or slave?

I guess what I don't know is how to rank these in best bang for the buck. I did a quick search on some parts and if I did all this, were talking about 5k just in parts. That would be a dream, but I would like to stay 4-5k including labor, so what should I get and what should I be able to get for under 5k? I'm afraid that heads and clutch alone will cost that much. Anyway any recommendations would be much appreciated. Also if you have any recommendations on some of these parts as far as brand or where to get them for the best price, please let me know.
Thanks.

P.S. About 80k miles on the car.