Chipr777

I have a 2004 4.8 ext. cab. K&N doesn't have a filter for the 2004 yet. They sent me an e-mail saying they'll let me know when it come available. Should I wait for the K&N or are there comparable units out there at a decent price? Suggestions? I also just added true duals and 40 series flowmasters. They're a little loud for my tastes. I dont like to hear it so much in the cab that I have to wait till I get at a steady speed before I can hold a conversation. Should I change out the flowmasters or is there anything I can do to quiet them down without hurting performence. Thanks for any suggestions on both my questions.

Chipr777

anyone know????

Musial-6

I don't like K&N. To much plastic. I like the AEM Brute Force or Airraid. I don't know if they are available yet either though

TXAGG05

I think thats just the nature of the 40 series. I had them on my first truck and they only got louder as they got broken in. It would be a shame to trade them out after you just paid for it and had then put in, but I don't know of any way to quiet them down. Maybe someone else does.
Jeb

1991FZR600

How do you have your tailpipes? All the way back past the bumper? What kind of tips are you running? Diameter and length?

Chipr777

The pipes come out about an inch past the bumper, including the tips of course. The tips are large, I would have to measure to be sure but i would say they're 24 inches long 3-4 inch diamiter.

1991FZR600

As for performance with true duals you should have 2" inch diameter pipes to keep proper backpressure or exhuast velocity(sp). That standard 2.5" inch piping that most shops use is to big. Here are some calculations that I took from someone else.....

Area for a circle (section view of a pipe is a circle) is Pi (~3.14) times the radius (half of diameter) squared.

So here are some better values for area of different exhaust piping sizes:

2.75" = 5.937 sqin (STOCK)
Dual 2" = 6.280 sqin
3" = 7.065 sqin
Dual 2.25" = 7.948 sqin
3.5" = 9.616 sqin
Dual 2.5" = 9.813 sqin

You start to lose low end power by having to big of piping.

As for the sound those tips are a big part of the problem 2' feet by 3.5" inches that's huge and is causing a pretty good echo. I would trade up for some 1' foot by 2.5" inch to 3" inch stainless tips.