I had a 1982 that was stock with the exception of the RMB. I never had any trouble passing smog here in SoCal. I now have a 1991 S-4 and when the only mod it had was the RMB, it passed smog with flying colors
Since then, I have added the X-pipe w/o cats, and the performance chip and it will no longer pass emissions
The RMB does sound much better then stock, and probably give a couple of more ponies
