ACT has another flywheel that is not as light as 9.6lbs. It is closer to the Exedy.

There are a couple of people who driveshafts for the WRX and STI. There is a one piece carbon fiber one that is about $1500 . I am thinking the Drive Shaft Shop's 1 piece aluminum for $425.

 

i would recomend to clean up the stock fly wheel and to get the Perrin light weight pulley instead.

 

I thought the pulley caused other problems also.

 

if you have both it is like over kill and your engine will not be able to work well with the ECU. some flywheels do it, never heard of just a pully to cause problems, unless you go underdriver, witch i would definatly not recomend

 

What gain/benefit does the lighter pulley give you?

From what I have read so far, the 13.9lb flywheel could cause false misfire codes on WRX's due to only 1 cam position sensor. The Sti has 2 and will not throw a code. All the more reason to replace my 109k+ stock motor and tranny with JDM pieces. I just need to ditch the poor stuff they original stuffed in the car.

 

with a lighter pully you are lightening the rotainal mass. there is a formula for the exzact % ratio`s. but it is something like every 1 lb of rotainal mass that is lost, is = to almost 4-5 whp...

you could do a replacement flywheel that is very close to the stock weight, just a little bit lighter. not 50% lighter. and since it is closer to the stock weight you would be able to have a beefier flywheel. but personally i have nerver had one. but i have seen a good improvemt with the perrin pully. but it is something that you might have to tweek a little something here and there with your tune.

 

aftermarket crank pulleys have a tendency to throw off an engines harmonic balance which wont cause any big problems right away but will just mess up the engine over time.