So I suggest first thing is to try a 41021 style manifold on that 9886... then if that is too much then try the 053, then the other pipes you have..... Its hard to predict what will suit you the best.. Sometimes it doesn't take much of a change to make a pretty big difference in how a engine feels on the track.... The Clocked BTT really meshes will with the 9886/41001 and makes a whole bunch more HP then any of the other combos I have tested...On that combo that engine is a beast that rivals the 7 ports....However once you take that combo off the engine settles down quite a bit and behaves more as a tradition plus 4 series does.....IMO its a great engine because it is capable of being tuned from quite mild to quite wild with just a simple pipe/header change......... The stock engine likes the 9886 too, but nowhere near the same reaction as we get with the Clocked engine...