RS suspention any good.

2.5RS suspension is pretty good, it will help your car handle better without sacrificing much (if any) ride quality/smoothness. See if you can get the 2.5RS sway bars also. That's a good price, too, installing springs is not a lot of fun. I hate spring compressors, especially the ones you can get at Autozone.

Does your car have a rear sway bar? A bigger rear sway bar is a good suspension modification. Helps the car oversteer a little more.

For engines, save your $$$ until you can afford to swap in a WRX engine, that would be a good solution. Expect it to cost about $7000 for everything, including all parts & labor needed.

Bolt-on mods don't help most subaru non-turbo engines much at all. You probably lost a lot of low-end power with your intake?

welcome to the family, now that you've posted, you're an official fanatic....
-scott-