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Power upgrade guide for normally aspirated Subaru engines

We get many calls for upgrades on this model, as a guide to assist you we have created this list to save your time, guarantee your money is invested correctly and most of all give you maximum value!.

Can not be reflashed or tuned for any improvement, zero value here, ECU is a old design and inherently allows no improvement. 

Unless you have MASSIVE mods, and or a custom build engine the same applies to ECU above.

As the engine is relatively high comp, there iss very little to gain here. OK if you want to invest over $3000 in a motec or similar ECU then you will get some advantages, but frankly, for this $$ you are better investing it elsewhere! 

Engine pipe with long secondary pipes to add torque is the only value, 5 - 15 kw and up to 50 Nm can be gained, with the correct complete design.
WRX systems barely fit and only reduce back pressure and engine response with no increase in power.
A free flowing exhaust from cat back will sound louder but add no power. 

Other than a horrible intake noise no power here either.
MRT used to supply and fit ram pod style intakes, but with technology and recent testing and on the later models these were made  redundant
A replacement panel filter in the std airbox will save on future servicing but give no power improvement.

Items such as aftermarket plug leads, high capacity discharge ignition systems etc all will ad very marginal if any improvement.

Bigger injectors empty your wallet and add no power. Save your $$ for suspension and get some GOOD improvements.  

OK if you have big bucks a turbo upgrade will add power, but really, why not just buy a WRX!
To turbo the NA engine you need a minimum $7000 to do a half decent job and still its not where near like a WRX
Internal engine mods are then needed for reliability.

OK like above if you have wads of cash, thena  rebuild will give some benefits, but a rebuild will cost over $5k and then you need to choose carefully. 

Is the car serviced correctly because often a service by a workshop who really knows subarus will be your best place for power.


  • Upper engine cleaner and in tank fuel additive. (when was this last done, its a subaru suggested option).
  • Good quality low friction engine oil such as Mobil 5 w 30 will give around 5 kw and better fuel economy over a non synthetic oil.
  • Fuel system service, MRT offer this and often get good results, cleans the EGR "gunk" out of the intake and combustion area. Also injectors as well as inlet manf and exhaust as well as fuel pump, lines and sensors.
  • Synthetic trans and diff oil, again like engine oil this adds up in benefits.
  • Timing belt, fuel filter are again areas that should be checked and renewed.

check out the performance / suspension section for REAL gains and benefits.
If I owned a NA suby, I would invest my budget in brakes and suspension as this is guaranteed BEST VALUE!
more here 

Refer the MRT vehicle service section here and take advantage of our free 78 point check to ensure your car is in top shape!

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