SSI's are sexy, sound great, and add a little bump in power at around 2500rpm righ where we can feel it. Other than that a cat bypass usally can match it in peak TQ and HP. A sport muffler makes a differance to.

The complication with going to SSI's is you can not fit a legal cat for smog if required.

somebody needs to fix that - cat technology has changed a lot in the last 30 years

anyway, since your interest is in more pow-pow for street driving at a cost that precludes an engine swap, you should find out how much the fines are so you can add that to your cost with a risk factor multiplier

I hear that they have all sorts of new programs to check cars on the highways as they go past entrance/exit ramps.

Grass Valley is near Yuba City, so if you take I-5 or I-80, I predict trouble at some point.

Sure you don't want to put on some nice poly-bronze suspension pieces? You'll be able to feel the road a LOT better.