Before we start a motor doesn't know it's being boosted so there is no way to tell a limit of boost. All it knows is that it is being made work allot harder therefore putting allot more stress on parts within the block. I don't think 1 person could tell you what the max boost you could run before you blow your motor is going to be. Tuning is something that needs to be added to that factor.....ok.

without a doubt 4gs aint enough but it'll get you started. You can run low boost (5psi) on a shitty FMU setup and make nice numbers. I was running 5psi making 254whp for about 5 month. With that 4g's you can do close to that if not the same. Only difference would be I was (still am) running a custom kit with the Rev Hard cast iron mani. and tuning. Don't forget you have to pay to get it put in if you don't know what your doing. Is shipping included on that price. What I'm getting at is if your on a 4g budget don't cut it to close to that because they'll be a few other things you'll need that you never hear of till it's time to put everything in. I had my car tuned to run as good as possible at 5psi. It was good enough for what I had but I wanted more power. If I was going to run a "kit" it would be the RevHard though without a doubt. Let us know if you need anymore help or have any questions.