i've recently blew out a spark plug on my 1999 GT which i hear is pretty common and i went with the insert to fit this. But i'd like to buy new or used aftermarket heads. need help on what set would be the best bang for buck as i am on a limited budget and do they really incress horsepower on a stick mustang with a few exhast upgrade? some help on where to find these would be good too i've seen a few adds on the classifieds that to me seem like a good deal but i'm no pro at this.
thanks,
thanks,
