subaru undedrive pulley and header questions.

so, ive read that the ebay borla replica headers like to crack, and that you can weld a support into them to make them more reliable. does anyone have a picture of the location of the crack?

also, since the engine is coming out for head gaskets and timing belt, im thinking of doing a lightweight aluminum underdrive pulley set. I found some insanely cheap for the 2.0 wrx, but don't know if these will interchange. also, any longevity problems with the underdrive?

any feedback? im looking to get some more pep out of the car 2002 2.5gt (NA) legacy wagon) and hopefully some more mileage. daily driver, no racing. (well, ill probably autocross it in CCRSCCA until I get the red car back together, so one autocross a month tops until mid summer)

Michael

I was under the impression that underdrive pulleys are a true full race item, far more trouble than they're worth on the street.

I'd avoid underdrive pulleys. First of all, they may not spin the alternator fast enough at idle to keep everything running happy if it idles for a prolonged period. Second, I've heard of them causing oil pump failures.

In reply to BrokenYugo:

It's the underdrive crank pulleys specifically that are usually a bad idea, as far as I know. Most of them replace your stock harmonic balancer with a solid pulley that does nothing to dampen crank vibrations like the stock piece, which I am told is extremely hard on rod bearings. On the other hand, I've run alternator, water pump and power steering underdrive pulleys on a few BMWs with nothing but positive experiences; I would think that the non-crank pulleys like these would be fine on most newer vehicles with under stressed cooling and charging systems. An early 80's import with an already-too-small 60A alternator and weak water pump...different story!

Bad juju, the little rubber strip around a crank pulley that makes it a "dampener" does way more than people imagine, it takes out the bad vibrations that would otherwise resonate throughout the engine doing everything from breaking oil pumps (cast gears resonate just right and break) to literally backing out flywheel bolts (dumb guy I knew would rather tighten the bolts once a week than but the stock pulley back on an ls motor)

So, no go on the crank pulley. Got it

I put an underdrive pulley on my ZX2SR. Best bang for the buck. No problems what so ever. worked fine even in winter.

Huh. Ive got a billet lightweight crank pulley on my 2.5, came that way at 260k miles. Up to 284k now and it hasnt blown up yet. Should i be worried?

I have avoided the non-balancer pullies on my miatas, but they regularly see 7500rpm. Subaru does not.