Originally Posted by Razathorn

BTW, I thought I would chime in to say that I really need to try a 2013 or similar as the jp-4 really doesn't match the bottom end of the rpm range of this motor. I think that, because the jp-4 is a more restrictive pipe, that it floods the motor with more fuel than it needs on the pressure side. The motor seems rich, a lot, but it's not. If you keep it cleaned out, it works great, but it loads up quite easily if you're not right on on the low end needle and keeping it clean. I know the low end and high end is set right and the temps last night were in the 220 - 230F range when the motor was absolutely ripping, but just sit for a few moments, and it really comes off rich, even if the idle hasn't changed for being loaded up. The LSN sits right on the edge of either being able or not being able to load up at idle -- load up time is in the 20 second range. It's also difficult to get the motor to warm up because it seems so rich initially.

I'm betting these are all pipe things.