ok,i have a 08 truck 4.7 v8... i had a cherry bomb and duls ran out the side..now my gas milage is crap..and i mean big time crap...any reasoning for it..i am considering have the original system put back on. but i really like the sounds of my new exhaust...any help!...

 

umm depends on the size exhaust pipe you put on it...and also is it true duals? what im getting at is maybe you put to big of pipes on and you dont have enough backpressure...if thats the case try using a single in dual out typ muffler...for duals...if you dont have enough backpressure you loose ALOT of torque at low end and gain HP at higher RPM's wich doesent help with gas mileage at all..

 

thanks for your respones...i have 1 in 2 out. the exhaust is 3inch like factory going in and 2 inch out..

 

it could be that your just getting into it alot more to hear it, thats my problem but i dont mind a little more gas now since its cheap

 

oh yea, i love it!..but i did run it on the hwy for 6 hrs with super in it and ran it empty and filled it. i was on the cruze at about 75mph, useualy i would have got 19 and that time i got 15. so who knows really. i just got them last sat. i am going to keep an eye on it, see if its my foot or something with the pipes...

 

the shound will also change in a couple months once the mufflers broken in...mine did anyways sounds much deeper now..but i got a flowmaster 40

 

hell yea! i got the cherry bomb they told me it was the cheaper of the flow master but served the same purpose. looks like on your truck the pipes are just behind the back tire.that is where mine are also. i am happy gas is only 1.42 where i live other wise i would be trippin big time.

 

i keep hearing about all this backpressure stuff, and had been hearing about it for years. however i read an entire book on "How to Build Max Performance Chevy Small Blocks on a Budget" and several other in his series, and he said that all the backpressure talk was nonsense. then again he was talking about max hp, and building faster cars, which means burning fuel faster. i dont see how backpressue effects the engine. i see it as the same engine doing the same amount of work, only now being able to breath easier.

 

yea i was told the same thing by a few other people. all i know is my gas mileage went down and i was hopeing for it to be better. dont make sense to me either but who the hell knows..lol

 

im with ya on that one i dont really understand on how it works i just know that it does effect it big time...i had a ford 4.2 V-6..and i had a single exit exhaust in front of the pass tire.....well i cut the pipes to make trual duals and didint get around to putting mufflers on it...bad idea, it was a dog especially with 285's on it, but i traded it in after that so i didint have to live with it very long ..