2007 WRX Upgrade questions
 

Hi Guys,

I'm making the following mods to a 2007 WRX Impreza from std.

Full decat with 3" system all the way through
VF48 Turbo with 3 port boost solanoid
STI intercooler
Apollo K&N cold air induction kit
Walbro fuel pump
folllowed up with a remap

What sort of power do you think I'll be looking at when done (safely)?

Can anyone recommend what plugs I should be running as I'd also like to replace them?

Thanks for your help,

Paul

Prob about 330 bhp and 390 lb/ ft torque but make sure you save a few grand to allow for a new gearbox, diffs, hubs, drive shafts etc

Are these something I should look to replace soon or just things that will begin to let me down over time?

all depends how you drive mate,im quite sure the newer gearboxes are a bit tougher than the early ones so you maybe ok for a while but i would save up for a 6 speed

You probably don't need the cold air kit at that level, and it may cause problems. The standard airbox with a replacement panel filter, e.g. K&N, is fine up to power levels that would wreck the hawkeye wrx engine. The engine isn't the most solid Subaru have done, and is somewhat weaker than the 2.0l, power levels much above 350bhp, and boost levels above 1.25 bar, run the risk of engine failure. Keep an eye on the head gasket in any case, they tend to fail at about 30,000 miles on the hawkeye wrx regardless of tuning. If they do go, it's a good opportunity to look at stronger head studs and forged internals to allow more power in future. Not cheap all round, £1500 just for the gaskets, so worth saving up for.

People's mileage seems to vary with the hawkeye 5 speed box, some are doing okay with 400 ftlb others say 350ftlb as a maximum torque. Worth talking to a sympathetic mapper who's done hawkeye wrxs before and knows the limitations of the rest of the drivetrain.

The usual recommendation for plugs are NGK PFR7Bs

To make the most out of the upgrades it's worth thinking about Harvey's ported and wrapped headers and uppipe. They'll improve the spool and torque. harvey does these on an exchange basis, also does a very reasonable price on turbo fitting, and can arrange mapping or you can drive off boost until you get to your mapper of choice. Saving money on the cold air kit can pay for the headers. I got him to fit a turbo, supply and fit wrapped and ported headers and uppipe on exchange, and supply and fit new plugs, all for about £570. You can find him on here

HTH