With stock ports youd need to bump up the pressure ratio to huff more air through them vs bigger ports, which means you need a efficient turbo, and/or a good FMIC. Alky injection could be helpful as well.. and for gods sake get a standalone, man.
From what little information I've gotten from the FC CPU, its junk. Personally I'd go with MS because its not ridiculously expensive, but thats me.
Also, supposedly someone got 400 whp from a stock S4. I forgot where the thread is, though.
The TD06-20g is on average a 350-375 whp turbo on a 2.0L DSM. Sure it might reach your horsepower levels, but at the level it'll probably be wheezing pretty good. I like Mitsu turbos but they are so outclassed these days by newer technology. They are pretty much cutting edge for 1970. I'd recommend a 60-1 hands down, or better yet, something GT-series.
hell with a GT series turbo, UNLESS it's a 35/40. The compressor map for the 60-1 is just about PERFECT for a 13B running 12psi of boost (i.e. 330rwhp). Use a 60-1 compressor, P-Trim exhaust wheel, and something like a .84 divided exhaust housing, or maybe even one size down for crazy spool.
You will NOT be disappointed =)
1990 RX-7, 60-1 compressor, .84 divided hotside. fun.
Best you will find out there for this power range. If you can afford the extra 400 bucks (GT35R is the same as the 35/40, and they run about US $1300 IIRC, while the T4 60-1's are about $900), go for the GT35R. probably 500rpm earlier spool, and faster transient response with the same power potential. nice =)