What Modifications can i make to my 09 2.5i Impreza for more power and better performance? would it be best to swap for the sti engine or just put a turbo on the engine i have now?

nope, that's like putting a better exhaust on your horse and hoping it runs faster. not quite that bad, but closer than the other way round - lots of effort for tiny gains.

 

It depends though - if you want actually fast 0-60 times then it's true. If you just like to tinker yourself and play as a hobby, or want to feel or look or talk about being faster with a few friends, or have a list of mods to put in signatures and Facebook, with small gains then do whatever you want - custom exhaust, lightweight pulleys, significant weight reduction, lower the vehicle, lightweight wheels and tires, see if anyone is doing higher stall torque converters or valve bodies for CVTs if that's what you have, remove your AC system. Then you're in a couple thousand dollars with meager gains and still getting killed at the track.

 

NA (normally aspirated) engines don't respond like FI (forces induction) engines due to basic laws of physics, people are under the misconception that "mods make more power". That's inaccurate. "Mods on turbo engines make more power" is accurate. They respond drastically, but your engine does not.

 

So yes a complete turbo swap is in order. That will most likely require a complete custom ECU controller and tuning which is highly involved and technical.

 

I'd just buy a turbo vehicle, much simpler and cheaper.

Edited March 20, 20179 yr by grossgary

What he said. Subaru did their job very well. You wont really improve much. Best you can do as is would be to reduce weight. Clean out your trunk, delete the AC etc.

 

A turbo on your existing motor means brief HP gains up until you blow the motor. Not a realistic option.

 

Simple way is to sell this car and buy a turbo model. If you're stuck on this car the realistic way to gain power is a motor swap.