SSmith

My car is in my sig. On a stock car will long tube headers w/high flow cats & w/dyno tune improve my gas mileage MPG?

BigBirdLS1

I can't be 100% sure about the mpg increase. Logic does tell you that if you increase the amount of exhaust being removed from the system that increases the efficiency which then will increase your mpg. However longtubes effect each car differently some run rich,lean,or just fine. It just depends on what the tuner has to do with your tune.

omarrakeen

iTrader: (2)

^ true. id say if everything was working as it should ( O2s and A\F ratio) you should get better mpg all day long. providing you drive like a normal human being

black_phoenix

iTrader: (27)

Agreed with responses above

mthegodfather

iTrader: (4)

Technically exhaust should improve MPG's. Most will see a drop though because of changes in driving habits after doing the exhaust.

TheBlueKnight

iTrader: (4)

My gas mileage stayed about the same after my LS6 intake/ Long tube header with high flow cats install and tune. Around 28-30mpg hwy.

ULTIMATEORANGESS

iTrader: (4)

exactly.



youll want to drive it harder with LTs. what fun would it be otherwise?

SSmith

Should I get 1 3/4 or 1 7/8 or Stepped 1 3/4 - 1 7/8 Long Tube Headers?

I'm eye balling Kooks stepped headers.

Thanks everyone for your help.

TransAmWS.6

I would probably go with the 1 7/8, but the 1 3/4's would work absolutely fine for your application. It's just that it seems with the 1 7/8's you have more room to grow if you plan on modding the car heavier in the future.

jimmyblue

iTrader: (11)

I doubt you will see an improvement. More likely the headers will make
your O2 sensors sleepy and cause overfueling by mistrimming, and even
when working they will be slow and swing wide.

Theoretical efficiency is all well and good, but there's plenty of reality
going on and not all of it's helpful.

LeanPocket

iTrader: (6)

depends on your tune and how aggressive it is from my experience