Ok, I got my K&N FIPK for my truck the other day and installed it today. First I wanna say WOW did it liven up the rumble of my 4.7. There is a bit better throttle response also, so I'm happy, just cant wait for my Exhaust to get here...should be here mid week.
Anywho, when on the testdrive, i gave it some gas and accelerated for a while. You can follow the RPMs, and as soon as you let off the gas, and the RPMs drop, there is a "tsssssssssss" sound coming from where the FIPK is. This is probably a stupid question, but is that normal? I know its bringing in alot more air, I just wanna make sure there isnt something possibly hooked up wrong or an air leak there. All the lines you had to take apart seem to be completely put back together, I cant find any cause for the sound, I basically want to check to make sure its normal. Thanks for any imput!

 

yea that shud be normal its just the air getting sucked into the filter. same thing happens with my home made one but mine is more notiable, its mad crazy when i pull up against a ricer and i revv my engine and his head moves faster than his rice rocket at full throttle, as he says woah wtF?

 

Well I took it on the highway today, boy can it get loud. Its very quiet at lower RPMs, but when you lay into it....there is only one thing going into my eardrum...the engine. Thats gonna take some getting used to.

Stupid question #2....it has somewhat of a funny sound...there is a rumble, but it just sounds "funny". Could that be because so much more air is going in and the same amount out? Will my Catback system help that?

 

welll when i installed mine i noticed my exhaust had more of a rumble