Would a 3" downpipe with highflow cat. make gas mileage increase or decrease? i have a 2001 GTP bone stock about to get exhaust soon though.
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02-02-2011
Would a 3" downpipe with highflow cat. make gas mileage increase or decrease? i have a 2001 GTP bone stock about to get exhaust soon though.
02-03-2011
It'd increase you gas mileage...anything that lets the engine breathe better will increase it.
Dont just get a downpipe..you'd be much better off with a set of headers. Speed Daddy makes a decent set
1997 1998 1999 2000 PONTIAC GRAND PRIX 3.8L V6 HEADERS - eBay (item 170469647635 end time Mar-02-11 16:41:03 PST)
All you would need then is a highflow cat welded in.
The headers outflow the stock exhaust manifolds greatly, as well as the downpipe.
Plus, you'll pick up even more gas mileage, and help get rid of any knock retard you currently have.
Going from stock exhaust, to those headers, I grabbed about 5mpg in the city, and about 10 on the highway..seen over 35mpg on the interstate cruising.
But there are write-ups on how to install those headers. They are one of the single best "bang for the buck" mods you can do
02-03-2011
thanks man
02-03-2011
i been reading about exhausts and i see alot of people taking out the resonator and putting in a glasspack? what does that do? sorry im a noob when it comes to cars.
02-03-2011
well after headers these cars tend to get a lot of drone. a glasspack IS a resonator. personally i like the sound with them. Cherry Bombs are the way to go if you want a glasspack
02-03-2011
thanks for the info guys
02-03-2011
Yeah, np.
For exhaust, the best setups tend to be
Headers, into either the stock cat back. Or if the mufflers/resonator are bad, get the longest, fattest glasspack you can for the resonator, and your choice of muffler.
There arent any performance gains to be had by replacing the cat-back, unless you are in a very high horsepower build.
02-03-2011
For info...
click the link in my signature.
02-03-2011
I just here a car running? It doesnt give me any info lol.
02-03-2011
Not to thread jack but a Catless downpipe. Will that hurt the MPGS? I know I have to get a tune to get rid of the code but wont the rear O2 read wayyy off still? How longcan I go on a Catless downpipe without a tune. Sorry same topic just catless pretty much
02-03-2011
nothing that opens up how the motor flows will hurt MPG, it will only help.
02-03-2011
that ^^Originally Posted by machinegunsquid
And the rear o2 isnt used for fueling, just monitoring, as far as I understand. So just use a o2 sim to keep the computer happy.
02-03-2011
Ehhh I should just get Speed Daddy headers if is can get over the slip fit part. Not sure how that works. Well I get it the rtv seals it and the clamps in turn tightens it all down. Just seems more complicated in my mind
02-03-2011
Nah, slip fit is simple....getting them welded is even simpler.
Mine are clamped with band clamps, and have never leaked.
02-03-2011
The whole welding thing = Money... Only if there was a writup with pics so I could play it out in my head............................... Oh and your car for some reason just screams RACE MEEEEEE. Anyway we will see gotta sell my GoPed pipe first lol. Apperently when you get married you have to choose what you want fast if I knew that before I woulda wore a..... anyway off topic AGAIN lol
02-03-2011
o2 sim doesn't work with 04+
Originally Posted by KeithGTP03
02-03-2011
You should be able to get the crossover welded on one end, and the downpipe welded for about 25-50bucks, depending on the shop, and how much you shoot the **** with the guy.
And yeah, my lady blew the motor up in my car...
she wants a different car now..
I told her "as long as I get mine back, and it runs, you can get one"
as far as the race me...its seriously the fender stripes...
before putting them on, I would never have people mess with me...after I did though, seems like 1/2 the cars im around do...
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