Very interested in a partial (full?) delete and tune after I'm out of CPO. A few questions I have it: will everything look OK/factory on the OBD2 side? In CT they do test emissions by checking the OBD computer and making sure everything looks OK. There is no "sniffer" test for OBD2 cars. Will it pass?

If I were to do a partial delete, what makes sense? What piece of hardware does it make sense to delete first? I ask because ease of reverting to stock if I ever sell it is a concern. I wouldn't want to rip out the tanks and piping for the DEF system.

__________________
2012 X5 35D - EGR delete and Stage 2 tune
2003 M5 - Imola/Caramel, Dinan S2 suspension, Alpha-N tune
1990 M3 - CF Airbox, Alpha-N, Schrick 284/276 cams, VAC S2 head, full GC suspension
1991 M5 - Black/Black - stock
1991 325iX - Winter beater

Retired: 1999 328is 5MT, 1994 525i 5MT, 2003 530i 5MT, 2012 X3, 2006 325i 6MT, 2001 M5