I don't know anything about Pulley modifications, but I'm pretty sure they are safe if installed correctly and you will see some gains. My friend at Secret Service Auto here in Houston said $140 to install.

It only comes with one. Had to buy two. I got them from advancespeedshop.com
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2 x Injen Hydro-Shield Water Repellent Pre-Filter (Black) - P/N: X-1035BLK (INJ-X-1035BLK) = $36.16

But I was looking at their site just now and it seems the price went way up. You can probably find them elsewhere for cheaper.

Hey buddy! When u bought a hydro-shield for your injen system is that come with a pair or just one pc? And how much u got it all? Thanks!

This is the one I got: Two - Hydro-Shield Water Repellent Pre-Filter (Black) - P/N: X-1035BLK

My advice would be to get one of these just in case: Injen Online: Hydroshields

I went through 3-4 inch puddle thinking there wouldn't be a problem and the injen intakes sucked the water right up into the engine and hydrolocked it. I had to replace the short block, $9,000 repair. Luckily it was covered by insurance.

I haven't had any problems since putting those socks over the filters.

Hi guys! Sorry if I post this on our group. But I just need help badly.
I just installed my injen CAI and everything was fine! But I'm kinda worries about the rain/flood here in Houston! Anyone of u with injen? Or have u guy heard about the problem of injen on our z? Any advice will be really appreciat! And all I need now is put back the front bumper but will wait for u guy to respond and I just want to prevent the sucking water happen in any case. Thanks a lot Houston z members!!!