Lean is not an issue for cats. They are a catylist. They only react to what is introduced. Rich, that will deff overheat and clog them.
As for the SAP. I'm glad I educated myself and found it and all. I am worried baout the check valve though. I may take it apart and see about cleaning it. Or price a new one. The SAP blows air into the exhaust system so the unburned carbons have a Oxygen supply and a chance to further burn off. Only works when the car is cold as about 10 minutes later when your Cat is up to temp the SAP is not required.
DD: 2003 530i 5spd manual sport package. Conti DWS's, Llumar ATR, White LED lighting. TLC on-going.
Garage queen: '07 335i Sedan, base pkg, 6spd Manual, Procede 3 V5 w/NLS, staggered 18" 313's w/Conti DWS's, HKS Exhaust, OS Giken TCD LSD, VAC Street Diff Cover, Akebono Euro Pads, CDV Removed, Black BMW Grilles, Interior & Exterior white LED lighting, LUX Angel Eyes, Debadged, Llumar ATR Tint.
Last edited by FLE39; 11-17-2012 at 05:46 PM.