I've been digging into this subject pretty deep here lately and for those that don't know anything about it, like I did, here's what I've learned. There will be another part to this and for me it's going to be the Dobeck AFR. ( air/fuel regulator ) This is the only one made specifically for the P5. Not just off the shelf either, you order it, they build it and you get it in about ten days. Called them and got the skinny on the whole thing, good people that know their sh**.
The factory O2 sensor only works at idle and low rpm's and it runs pretty lean stock. When you add the aftermarket exhaust/intake you're creating more air flow, the factory O2 sensor will adjust and not go into error or anything because it's only sensing the low rpm's. It doesn't sense anything at mid range or high speed and again will not read the trouble even though you'll be running very lean, not good. Installing the AFR regulates the proper amount of fuel for the amount of air flow. It has factory settings so it's just plug and play but allows you to tweak it if you choose. You even add a second, wide range O2 sensor, that you drill into the pipe to monitor the under load flow. I asked the guy if he thought the exhaust and tuner would make much difference on this machine and he said most see a 10% gain in HP. For us that's about 2 1/2 horse which isn't very much but should give it a little more ass anyway.
Even if I can't keep up, you'll hear me behind you.