300KW stock STI block and bolt-on turbo!

PBMS modified and tuned V9 WRX using a stock V7 STI block. Producing 300kw+ at the wheels

The Magic 300!

It wasn’t that long ago when producing 300kw was a massive deal, however advancements in engine, turbo and tuning technology have made this magic number very achievable.

Lance originally came to us with his limited-edition 2005 WRX wanting a staunch and responsive power increase. The initial plan lead us to upgrade the tiny TD04 to a larger VF30 STI turbo, supporting it with a V11/GRB STI top mount intercooler, STI injectors, fuel pump and Link ECU. An exhaust and intake pipe were already fitted to improve engine efficiency. Once tuned, the vehicle put down a playful 236kw at the wheels.

With a background of fast cars, it didn’t take long for Lance’s hunger for power to get the better of him, and he was back, for the next level of modification.

The Plan

Our sights were set on 280kw at the wheels, with a minimal sacrifice in response. The first port of call was to refresh the 200,000km+ engine. The most economical way to meet the power goals reliably was to fit a brand new EJ207 shortblock kit, and rebuild the cylinder heads.

To support the extra power, the EJ207 was fitted with a larger set of 750cc injectors, PBMS Hybrid TD05/6 (bolt on), intake pipe and front mount intercooler. To aid reliability and consistency a stainless turbo heat shield and cold air box/duct were fabricated.

Once the modifications were completed, ’05WRC’ hit the dyno to see what we could pull.


Engine Modifications (Initial stage)

Link G4+ ECU
VF30 STI turbo
V11/GRB Top mount intercooler
3 inch stainless steel exhaust
Aftermarket intake pipe
STI fuel injectors
AEM 300LPH fuel pump
Pre-dyno peak power 236kw (at the wheels)

Engine Modifications (Secondary stage)

V7 STI EJ207 Block and rebuild cylinder heads
12mm High flow oil pump
750cc injectors
PBMS TD05/06 turbo (bolt on/single scroll)
Turbosmart twin port internal wastegate actuator
PBMS 3 port boost control solenoid
Front mount intercooler kit
Custom cold air box/duct
PBMS retune package



Note: Tuned on BP 98.

Both Lance and PBMS team hoped for around 280kw, and were hoping to maintain as much response as possible with the longer intercooler piping and larger turbo. Peak power improved from 236kw to 303kw at the wheels, smashing our initial goal, and breaking the legendary 300 mark! What’s more impressive is the power curve and response. The trade off for additional power is minimal on the dyno, and not noticeable on the road. In 3rd and 4th gear, full boost is seen at the 3600rpm mark. This creates a responsive drive, that has a huge kick to boot – very impressive for a stock block and bolt on turbo combination.

Blue line shows original setup and the red show the new, high power setup

Blue line shows original setup and the red show the new, high power setup

About the author, Julius

Julius provides technical support and expertise to Possum Bourne Motorsport. He's been involved with the industry since 2009 and has stamped his mark as an industry leader.


  1. Jean Bedejo on 05/15/2018 at 3:36 AM

    Hello Julius,
    Wanted to inquire regaring the cost for initial stage set up? And cost for secondary stage as well? With this type of modification, do we have to worry regarding reliability of the engine in the long run? Especially for people like me who does a lot of long distance driving…
    Im in Christchurch and I have a 2004 wrx nearly 200k’s on the clock..my future plan is to trade it for a later model but considering this initial or secondary stage set up. My only worries is reliability in the long period of time.

    • Julius Bloem on 05/29/2018 at 1:27 AM

      Hey Jean,
      Reliability and performance always take thought and balance. If your engine is in good condition, then there is no reason why you couldn’t see reasonable power and reliability. Without disassembling and stripping the engine however, there is always an un-known, especially as the kms get up. Drop us an email at patrick@possumbournemotorsport.com to discuss a package that will work for you. Regards, Julius

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