I just put a set in last night, the "300's" I don't know if they are any different than the 275's but I'm happy with them. I get mine from Scott Goff in Utah, -- email address removed -- is his email, give him a shout, I got mine for 295 shipped to my door, with no core charge. I ordered them tuesday and they showed up thursday morning, so I'm happy with that. The swap is pretty easy. I will say this though, I'm used to 12v. And made the mistake of pulling my injector lines all the way off, kind of a pain in the ***, but it gives you a little more room to work (I guess). Doing another set next week in a buddy's truck, I don't think it will take more than an hour and a half. So far I'm pretty happy. Definitely noticed a difference. The truck makes a little smoke now, with it set on stage 5.