whats next?

Have you hogged out the E6?
What's the specs on the T-3?
Cam?

I would port the E-6 or get a header and do a good 3" downpipe.

This won't get a lot of power but it will sure free up the engine and help with spooling.

I think you are at the point where you need to spend a bit of money and time to get any considerable amount of HP
IE; head work

The biggest upgrades I would recommend are:

- full 3" exhaust (from turbo outlet back)
- T3/T4 hybrid turbo
- better intercooler (from an Isuzu NPR, Spearco, or a Supra)
- turbo-specific cam (don't know a good place to get one though)
- port the crap out of the heads, and get big valves
- rotate the intake manifold 90 degrees toward the front, for less piping to the intercooler (http://msvorinich.itgo.com has a good picture or two of what you'll need to do)
- get a good exhaust manifold (http://www.turboford.org/ A couple members make bolt-on custom ones that are proven to add 15-20rwhp)

All these mods will push the output to over 300rwhp. That'll put out easy 12's in the quarter mile.