Here is my dyno testing after installing an under drive pulley from Alamo Autosports. A very noticeable 12-5WHP is measured across the power band, and the new crank pulley is about 5lbs lighter. I have an BLITZ turbo timer so I was able to monitor voltages before and after. There was no significant change in voltage, maybe .2-.3V lower, even with AC, lights, stereo. Other than the engine reving faster and better acceleration, I would not know the smaller pulley was there.
I have used under drive pulleys in other applications with no reliability issues accept minor voltage fluctuations at idle with light,AC,etc. That does not even seem to be a problem with this car, possibly due to the slightly higher than normal stock idle. I have also talked with several DSM/WRX owners who have used under drive pulley's for years and experienced no reliability issues. So save the gloom and doom BS, I already posted a queery on this forum and got nothing but positve feedback.
Bang for the buck IMO this is probably one of the best mods you can do to your car. It is stealthy, and most likely will improve the reliability of your accesories, especially if you spend a lot of time running high RPM.

 

Nice Dyno numbers! What mods do you have done besides the pulley. I'd like to get one of those . Are they going to sell these soon, or are you still in the testing stage?

 

Ditto!

 

I have a turbo back 3" exhaust (RMR) with a Random 2.5" high flow cat (going to 3" cat soon), A K&N stock type air filter, Greddy type-s DV, EBC Greddy prfec B specII (running 19.5-19PSI), oh and Red Line synthetics in the entire drive train.

 

Very nice.. Can not wait to get mine installed tomm. and tested. hope i get some of the same results.

 

Hey Silver Surfer, it looks like getting to that bottom pully is a real pain so what did you have to do to get the stock piece off and the aftermarket on? About how much is the pully?

 

Oh and this is an in stock part that can be purchased right now. The kit comes with three pullies but I just did the crank pulley, it's much cheaper and far easier to install. I could not honestly see any real advantage with the alternator and water pump pulley used in the kit, (they are the same size as stock).
Alamo has these in stock 817-860-4300.

The crank pulley is not that bad, you have to take the right front tire off, remove the plastic cover and the pulley and auto tensioner is right there. I watched but I did not install it myself, hey they offered to install and dyno test it. I like doing my own stuff but... it took them about 1/2 hour.

 

Very cool, I am glad that there is an access panel to get at it through. I took a quik glance at it from the top last night and could not tell if you would have to lift the motor or if you could get at it from some other way. I was kind of curious after tx evo said that he was going to have this put on. You know, overall I have found the Evo pretty easy to work on, i.e. to take apart and get back togather again considering all of the stuff under the hood. I have had a naturally aspirated BMW that was much more difficult to get at. You do need to watch the lip of the cooling fans shroud though, that little **** is sharp as hell! I have many many little slices to prove it, I was actually at the point last night to where I damn near went for the file to blunt the edge. Actually I think that I will take a file and blunt the edge, it will save me money on liquid band-aid.

 

I wish Alamo would improve the navigation on their web page. I do not feel like calling at the moment, but wanted to get a price on the pullies, where are they on their web page?

 

Got the t-shirt on that one and already smoothed the edges .

I know, they are supposedly working on a new web page that will have all of the EVO VIII parts. For now you just have to call them, perhaps some one will post the retail price.
Because I was willing to do some initial testing, I was able to get a discount so I don't know the actual retail price.