I have the 16g's myself, because I got a good deal on a used set. The 18g's lag more, but provide more top end power. I haven't heard any numbers yet on the 18g's ... hopefully Fred (Good2Zya) will dyno soon so we can compare. Most w/ the 16g's run 120-124 in the 1/4 on 18psi of boost ... which means they are putting down around 500rwhp. They are the mitsu style flange, but since the kit comes so complete, it's not a problem. Only issue I see is you have to get custom test pipes since the downpipes are different.