Quick question I bought a racing header with no cat so now my mini is missing the second O2sensor with that being said I'm about to buy the alta exhaust also has no cat.. Is having no cat or check engine light on bad? Check engine light was on when Jan in California tuned it though.. A little confused if I'll lose power with no cat and just a resonator and muffler and if the CEL being on I'm losing power but again the car was tuned after Help would be greatly appreciated!!!! Thank you!
The lack of cats won't cause a power but the computer might. If the car thinks its not running right because of the second O2 sensor is missing then you could have a power loss. Best thing is to contact Jan and ask if he set something up in the tune to take care of it.
only reason I ask about the power loss with having no cat is I heard supercharged cars need restriction and i didn't know if a muffler and a resonator was enough restriction. But that's best your right I'll contact jan see what he says! Thanks alot MRNTD!
On a s/c car, you don't really need any restriction. You want a decent sized exhaust tho. No point in dumping into a 4" exhaust if the engine isn't pushing enough to actually fill it. You could even lose a bit of power from going too big. Turbos need a bit of restriction up front, but once it's passed the turbo, it's better for it to be as free-flowing as possible.