Is there a big difference between the 57 and 77 series? I see on the K&N site that the 77 series is a bit louder and the 57 series gets a bit more hp but my question really is WHY?? What is the difference between the two (which look exactly alike) that makes them...well...different?? Does anyone have experience with BOTH (yes I know many of you have the kit but do you know about both??)?? I just bought my truck this week and hopefully it'll be my first mod. Since I'm not much for doing a whole heckuva lot of crazy appearance mods, I'd really like to make the engine compartment something to look at. I like the 77 series which is polished aluminum but it gets less HP than the 57 so I'm torn between the two models. Any advice is very welcome! Thanks!