Sorry if this is a very often asked question and if somebody can point me in the right direction to a guide then that would be great. If not then any advise would be appreciated.

So I've got a 55 plate STi currently has Japspeed downpipe, 3 inch cat back exhaust, Pro R Panel Filter, Walbro 255 fuel pump and remap running 330bhp but as im now used to the power and have the taste for more what would the next logical step be. I will have about £1500 for parts.

I was thinking some RCM headers, FMIC and tweek to the map (obviously not costing the full £1500). Are the headers worth it on the stock turbo and what sort of power would you expect to see from this set up.

I did think of going for a bigger/hybrid turbo but would it be safe on the standard engine internals?

I would love to see around 420bhp so what would be best to buy to reach that target?

 

Your engine is good for a reliable 400bhp, many running at 450+ with no issues. You wont notice much difference with the mods you mentioned at this level as your turbo is now the limiting factor. I was in the same position mate and bit the bullet and went for the bigger turbo route. Its the way forward and if you get used parts could be done within your budget.

 

His engine is good for a reliable 450bhp plus as it's the widetrack - best 2.0 UK engine, same as mine
Spend the money on an SC40, SC42, MDX321T Billet or equivalent.
It might be slightly over budget, but Japspeed FMIC's are £200 including an air filter (you'll need a dump valve adapter - White Noise (Neil) sells these) and you should still reach 400, then you can grab RCM headers at a later date.
Your injectors (assuming standard) will start to max out around 400bhp and you'll want to consider 650's or 740's to be safer.
A 3 port boost solenoid will also help better boost control.

Little point as said with headers - you'll probably make a little more torque than before but on a vf35 (IMHO terrible turbo) it's pointless.
If you're looking to go bigger power I'd throw a 290lph fuel pump in as well.

For guide - google Engine Tuner's / Engine Mapper's performance tuning guide - I think there's a PDF on here somewhere from Martyn.

 

Thanks for the help guys

Which turbo would be best for 450bhp? I dont want to be running the turbo on its limits as want it to last and also where is best to get one from?

I currently have a Japspeed FMIC at home ready to fit as well as a Devils Own Meth Kit that will finish being fitted when the FMIC is on.

So from what I can tell I would be best going for the following to get a good 430/450bhp:
SC40, SC42, MDX321T Billet or equivalent (Dont particularly want a laggy turbo)
740cc injectors (which make)
3 Port Boost control solenoid (again any particula make better than others?)

Hopefully with all those mods and im thinking a new map from JGM I should see a noticable amount of diffference.