First i would like to extend a preemptive apology if this has been previously discussed, because i know it has been to some extent... i searched a bit but could not find exactly what i was looking for. I would just like to get some more boost knowledgeable peoples opinions on this.

I've got a B13 SE-R with an avenir motor, GT2871R, 72lb injectors, JWT ECU, Z32 MAF, FMIC, 255L/HR fuel pump, JGY fuel Rail, Profec Spec II, and JWT S3's. Other than the cams everything internal is stock. Also 3" dp, gutted cat, 3" cat back. What is the MAX safe boost pressure that i could run with this setup for short periods of time (maybe 15-20 min) without F'n up anything. And also round about how much power would upgraded axles become a must?

You could run up close to 20 with that fairly easily. Unfortunately, that's where you'll be maxing out your axles most likely, since that's the 300whp area. 20 is also somewhat past the efficiency range of a T28.

Sounds good, thanks for the input. I had been running it around 18 (closer to 10 for DD) was just wondering how much more i could squeeze out of the t28. Never had this setup dyno'd tho (put down 221FWHP @ 10psi w/ the stock t25 and stock cams) Im thinking about moving up to a t3/t4 here in the future, would a GTi-R manifold work with that? or would i need something different?

I believe the flange is different, but there are adapters out there.

That setup you have is good for 400+whp. The GT2871R is a damn good turbo. You can run 20 lbs easily, but I would make sure you have some race gas to go along with that. On 18lbs you should be close to 400whp to begin with. You need to put that thing on the dyno. I would run 16-17lbs on low boost and crank it up to 20 on high. The only two issues you have at this point are your head gasket and the transmission. At this point I see no need to go T3/T4.

Oy, I misread the turbo designation. Nice catch.