What kind of power do you want? The Skunk2 is almost a direct copy of the stocker w/ similar length runners and size plenum. JG's got a short, tubular runner. Both are good IM's, but both are aimed at a different power delivery. The S2 delivers decent mid to high end power while the JG w/ it's short runners are primarily for lots of high end flow. Also the power gains from the JG won't be realized until very high revs. Be honest w/ yourself and ask what you really need: a broad delivery or a top end screamer. If you decide on the JG, I might also recommend you open up the head a bit as well as the LS will become a bottleneck in hi rpm flow.
