Read completely through the FAQ for some good info:
I think most of us will agree that your next step needs to be something to get the intake charge temps down. You need an IC or WaterInjection. Do you have PowerSteering or A/C? The low boost you're running now probably won't cause any knocking problems yet, but sumnmer is here and it's getting hotter. Without an IC, if you want to up the boost more than about 6psi, you'll have to pull too much timing for knock prevention to make it worth it.
After you get the intake temps down, you're going to be interested in a stronger fuel pump. I was running 1.8's really rich up to around 170whp @130psi of fuel pressure. Now I'm running 305's@100psi of fuel pressure @12psi boost for 190whp. Obviously lower fuel pressure is better, but I had no problems with flow in the 130psi range. Of course you can only run so large an injector on the stock ECU. 330's seem to be the recognized upper limit for good idle characteristics.
So, get yourself and IC or WI and turn boost up to 7psi. Then get a fuel pump and you should be set for 10-11psi. For more boost, invest in bigger injectors so you can get the fuel pressure down. You'll need a fuel pressure gauge and an assortment of Vortech discs. You can tune based on the match and other setups, or you can get a Wideband, or get on a dyno.
Just to make sure, you're using the highest octane available to you, right?
You have budgeted for a clutch? You'll need one above your current power level.
What other mods are on your car? Post some pics in the vbGarage and give a full writeup. Fill out your sig too.
You can install the cat/exhaust, get a decent IC, get an appropriate disc for the vortech, and you shouldn't have any problems running up to about 10-12psi on the