Not sure if this is possible with WRX, but my buddy has been clean his RS with simple green and seems to be working fine. Any thoughts? Thanks.

 

Just don't get the degreaser in anything electical.

 

If you don't have access to a steam cleaner, I've always been told that spraying down the engine bay (make sure its cool first) with simple green, then letting sit for 10 minutes, then hosing down the engine with low pressure water (like that from a hose) is a very effective way. I've never tried it.

 

Did it to my integra. Make sure it is not illegal in your area, Like it is in San Jose CA. Not sure if it is a state law or county ordinance.
First cover all electrical
Used mr gunk engine degreaser
Waited as can directions directed
washed off with water done.
Didn't know it was illegal til I was done and my old roommate told me

 

what i have done on all of my cars and friends cars, is cover all electrical as best as i could, then spray with simple green, let sit for 10-15 minutes, and then pressure wash it all off... it leaves a sparkle free finish.. but i only do that when the motor has thick gunk everywhere...

 

ive always used simple green and low pressure water to clean all of mine and have had no issues... I resion it this way.. companys spend multi millions to make the connections water proof. (to a point)