I think there are a few things wrong with capping it. First, I believe if you cut the oxygen sensor totally away from the exhaust stream, it will throw a code. So that eliminates capping it.
If you don't take it far enough away from the stream, you will still get exhaust strong enough flowing over the O2 sensor to throw a CEL for catalytic innefficiency. So I don't think you can cap it with holes in the cap.
Besides that, even if it did work, you would have to find/manufacture a cap that could withstand the heat of the exhaust, still plug into the bung holes, and fit over the O2 tip.
Why try and find a solution to a problem in where there is already an easy solution? If you can't fit it due to a transmission, you can pay an exhaust/performance/dyno shop $50-65 to make a new location for you. Most performance shops have to make one anyways for a wideband sensor anyways.
It's been 2-3 months with only one CEL when I drove over 200+ miles. Daily driving does not set it off at all. Good enough to pass an OBD scan for emissions, good enough for me.
2004 330Ci 6 Speed; UUC Sway Bars; Powerflex RTAB's and FCAB's; KW V2 Coilovers; 3.38 OS Giken LSD
Z4 Finned Diff Cover; Headers; M-Tech II Rear Bumper and CF Diffusor; CF Trunk; CSL Front Bumper
M3 CF Hood; DICE I-Pod Kit; JTD Rear Shock Mounts; UUC Front Strut Bar; O2 Simulators
ESS TS2 Twin Screw Supercharger
Last edited by Minnoe07; 07-23-2008 at 05:34 PM.