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  1. #1

    Default dual 40 series!!!low back pressure????

    aloha everyone!! so recent upgrades include a set of hooker comp headers and dual flowmaster 40 series exhaust! all of this on a stock 305... the truck sounds good at idle, but get on the gas a little and it sounds like a train coming through! but at the same time, it feels as though it lost some power on the low end, the truck makes a whole hell of a lot of noise, but doesnt seem like its moving the way it should. any ideas??? did i go too big on the exhaust??? thanks!!!

    1995 silverado
    Beltech 4"drop front soon to be 6" on the back
    true dual 44 flowmasters
    Hooker comp headers
    k&n cai
    20" zenetti throwback wheels
    2 kicker 10" subs
    alpine seps
    alpine mono 500w amp
    jl 4chan 500w amp

  2. #2


    Did you run the exhaust all the way out. Also what gears do you have in the truck. You cant expect a 305 to just blow the doors off. You may not be getting as much air in as you a pushing out. I suggest getting a cai.
    08 silverado
    K&N cai
    single in dual out cherry bomb pro
    leveling kit
    custom painted bow ties
    Bed liner
    Tinted windows
    20inch Cruser Alloy Switchblades
    Goodyear Eagle GT2 285/50/20
    1 truly heavy foot + Wait4meperformance SCT Handheld
    100 shot of Nitrous Dyno tune system
    SS front bumper
    Matching painted front grill and bow ties

  3. #3


    the gears are stock gears, not too sure of the ratio... i have a k&n airfilter in it...did you change the gears in yours? i was thinking of doing the gears, but not sure what to get... i know i want to change it to a posi, but for the ratio, maybe a 383??

  4. #4


    oh yah, cai? what is that?? sorry, i think i have to do more homework on this stuff... haha!!

  5. #5


    i got it!! cold air intake... hahahaha!!! what a rookie!!!

  6. #6


    i have the same problem, you need to google about BACKPRESSURE and read up on that. im not going to try and explain it but it can have some negative effects on torque when you change the exhaust from stock, depending on how its done.
    1996 Silverado
    *Mostly stock for now
    *Soon to be airbag project..

  7. #7

    Join Date
    Feb 2008
    Red Wing, Minnesota, United States


    Are your headers shortys or long tube? How big of pipes did your run and how was the exhaust set up?
    99 K1500 Suburban LT "THE BEAST"
    Hypertech III, K&N, true dual

  8. #8


    thanks for the info! it just sounds like the straw is too big for the spitwad! haha! now how to correct that is another thing!

  9. #9


    the headers are full length, the pipe is a 3" up and over the rear end not quite a 45 to the tips. but it is a true dual. from the headers, both individual pipes run to the passenger side of the truck, then straight back. right behind the tail gate, the pipes split to 45s then down. does this make sense??

  10. #10


    Quote Originally Posted by 1995 silverado View Post
    thanks for the info! it just sounds like the straw is too big for the spitwad! haha! now how to correct that is another thing!
    2 options for correcting it, A) change the exhaust setup, or B) increase engine power to raise exhaust flow.......or do like me and get used to it cause u know you like the way it sounds and you dont wanna change it!!!

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