I think you might be able to get away with MS in CA on a RB car. If done right it'll look stock. The biggest thing would be the cat. I'd knock out the innards and put a straigh pipe through the cat body, but reccomending you do so might be illegal. I'll find the link of ol' boy overseas who MS'd his RB and it started snapping axles.
JP, I think I found a way to install the euro carbs w/o cutting. I was working on it until I found the 5 speed, so I've been a bit distracted. I need to get on it again. Just the euro manifold and HIF's shouldn't be a problem.
Dave, MS is a fully programamble fuel injection system you build yourself. You'll have to build a complete fuel system from stratch, so you'll have to at least be willing to be handy. If you don't have allot of mechanical background, or just don't wish to bother with something that'll take allot of time, then a carb swap would be in line. The euro SU's are pricey (for what they are)and may be hard to find, but allot of folks recommend them. The biggest bang for the buck, IMO would be to swap to a Weber DGV.It's a bit cheaper than the su's. Some folks don't like them but I have one and it' does o.k. If you go that route, make sure you get a BRAND NEW kit, not a used carb. Bottom line you're not going to make any HP with the stock manifold unless you turbo it....and there'sa guy who's been through the wringer doing that. You can swap to another carb with your intake, but the intake is the bottle neck and chokes the car above 4K. ( but I usually never rev higher than that.)
Cheapest, easiest route would be put a Harley muffler on it and ditch the cat. VB has a pipe for that pt# 6-067 for around $40 or so. You should notice a slight difference, at least it'll sound better. Make sure to knock out the center baffle.
My car already had the smog stuff removed, but if it were me, I'd disconnect the vacuum retard, bump the timing up to 12-14 degrees BTDC, ditch the cat and put a Harley muffler on it for starters and do something about the stock air cleaner.
All this being said, I have a DGV and I'm swapping over to su's for now for milage and the fact I can easily adjust mixture. The only reason I bought the su's was I got a great deal on them and they came with all the stuff I needed to install.