Nice car I agree with what everyone has said. Keep the cat back you have. An lm1 is just noise. This coming from a guy with long tubes no cats true duals dumped before the axle lol. I love my ws6 I've owned it for almost 8 years. You say sad face auto I wish mine was auto so tired of breaking 10 bolts lol. As far as normal maintenance problems I've had my drivers side window motor go twice. That's about it. Everything else is from me beating it hard lol. If it were me first mod would be a stall.