Originally Posted by 135Pats
Sure you can, you'd just need to swap out to the OE downpipes for testing...Granted that is neither cheap nor convinient, it would probably come down to labor costs in your country, and how often you have to pass emissions testing.
I was thinking of going the catted downpipe route and people haven't passed emissions this way either. So I said screw it, do my emissions before Feb 16th, install the catless DPs and not worry about it for 2 years.
OP, you have to remember that you aren't guaranteed to pass emissions with an aftermarket catted DP, possibility of still failing emissions
Old| 2005 s2000: KPRO, Invidia q300 v4, PLM header, BERK 70mm HFC, Vortech v2 (3.6" Reichard Pulley), FMIC, ID 725cc (397whp/243tq @9psi, Tuned at Innovative Motorworks.
New| 2008 135i: COBB Stage 2+, ER CP, TiAL Q, BMS OCC, BMS DCI, Active Autowerke 2.0 Sport FMIC, VRSF 3" DPs, CP-E Axleback, Robs' PCV. Coming Soon: AMS FMIC, welded 3" cold piping; Protuning Freaks Protune