bluegtp chiped a pistion with a 3.5 and more mods than you. but that was with a zzp pcm. that was probably the majority of the reason right there.
right now your probably knocking. when you knock, the pcm pulls timing, i think max timing is in the 14* area, if you knock up to 7* thats half your timing being pulled. reduced timing=SLOW. exhaust mods always help out. and a programed pcm or custom tune is needed. more fuel ect for the 3.4. tunes make a BIG difference.
wires and plugs are not really going to help with knock, you can get colder heat range plugs, but you wanna try and keep the hottest plug you can with out knocken. moving air around more efficently (headers, plog, downpipe, rockers, cam, or intercooler) is going to reduce knock. but i would say you deff need exhuast work. catback is not going to do anything for you, you need something in the header range. save up some money, get some headers and do it right.
