Everything Iv'e read on these forums and elsewhere says we're not going to get much above lower 300's chp without fuel mods.
I too wanted 300whp too
With that said ...
I have (or had):
2005 LGT 5MT
rebuilt engine in 2014
(New STI Short block) heads redone
Assume factory stock parts and position except these mods
Perrin rubber inlet hose
BNR 16G
Avo TMI
Catless up pipe (Not sure of brand) Xtreme?
Cobb catted down pipe
Magnaflow cat back exhaust
Car tuned at TIC by Dominic in Mar or May of 2015
Ran out of fuel. 100% injector duty cycle.
Dominic said it felt like it could go more but needed fuel mods.
I asked him to turn it down to 90% duty cycle and I'll live with it until I'm ready for the fuel mods.
Result was ~236whp.
He recommended larger injectors and higher flow fuel pump.
It then became an argument between top feed or deatschwerks.
Something for another thread.
The following Friday, I weighed the car with me in it at a local scrap yard on my way to the drag strip.
Did several runs until I had them consistent and wasn't getting any faster. Then did the math for HP number. Dyno's aren't calibrated for accuracy like a truck scale is so I wanted to double check
The math said ~260whp.
Assuming ~21% (17-25) loss thru the drive train; that would put it at ~320chp. So, seems what I've read and is posted in these forums is quite plausible.
Keep in mind these are not definitive perfect numbers but just observed data with a few assumptions on the final math. it's not an argument for or against anything. So, poopoo what i've said or take it for what it is and do what you think you need to do to achieve your goals.
I have the parts to make the needed fuel changes and the plan was to go to an 18g if the fuel changes didn't measure up. But, car was totaled Aug2017 when I rear ended a ford expedition with a @#$%^ receiver hitch. Another story for another thread.
Hope this helps.