im away to stage 3 my cossie,at the same time im going to change the headgasket for a group a item,is it a hard job to do?theres nothing wrong with the gasket thats on,its possibly a group a gasket but its piece of mind.also im fitting a stud and nut kit,anything to watch out for with these?as for the rest of the stage 3 kit is that easy to do?(green injectors,map sensor,t34,044 fuel pump)my mechanic pal is going to solder in the chip for me.