Wanted to install pulley on my car, but am seeing quite a bit of them fly off. I know pinning helps. For people that have done the install, are the bolts reusable? Perhaps this is the reason that they are all flying off? Im talking about the stretch bolts, TTY bolts, the ones you can only use once.

Get a new OEM bolt and pin it...don't risk it.

OEM bolt and have it installed right, pinning is an insurance however pinning isn't necessary if the install is done right by an expert. My pulley has been on for 100k miles and no pin was used.