I'm thinking about putting in an underdrive pulley from Vishnu
in my WRX. Claim is +10-12 whp, and very little penalty.
Is there a consensus opinion on underdrive pulleys on our EJ20 engines? Anything bad to say, reliability-wise?
I'm sure this has been covered before :(

Not really on here as far as I have seen. There is a lot about it on I-club.

So not much experience with underdrive pulleys in the UK on the Scooby? Seems like a good gain in power just from reducing parasitic loss... just that I'm worried about extra stress on the engine bearings, or messing up the power steering.