Aloha guys, OK, I have an ls1 , just installed a mayhem 2 cam kit, 235/245 duration, 630 lift 113 lsa, have an ls6 intake stock, 78mm throttle body, stock, and 85mm MAF stock and descreened. Have the stock 241 heads. 36 lb injectors, short tube headers with straight pipes. Making 421rwhp, can buy my friends 05 GTO ls6 heads, or should i go with a 90mm throttle body and intake change.

 

I'd go with longtubes and a throttle body change. As you sit right now the shorty headers and your TB are your biggest restrictions.

 

Heads first IMO. I would even have the 241's cnc'd for a little more money and have a better flowing head as a stock 243

 

^^ Ls6 Heads next my .02