Bill currently I'm working on a 1j swap, and from my experiences.......I just rather of changed the 7m headgasket. I sure hope it will be worth it when I actually have a running car. The exaust wheels are ceramic..thats why you cannot turn the boost up anymore than 14psi. I'm just going to play with the twins for a few weeks to make sure the cars running right , then I'm just going to put a single on it and try to make some decent power.