Corsa Exhaust performance??

I have a 2000 Silverado Z71 with the 5.3 with a K & N Gen II already installed. When I bought the truck off of a friend he had a flowmaster 70 series on the truck. Well that rotted, so I purchased a Corsa dual rear exit. I was told with the less restrictive muffler that the Corsa would sound better and give more mpg. However, since I have installed the Corsa I have went from an average of :smile: 16.3 mpg to 15.5 in the summer and 14.7 to 13.5 in the winter.:disappoin I even drove 2 complete tankes under 2,000 rpm. One of the tanks, I even kept it under 1800 rpm for the entire tank (which wasn't easy). Any suggestions why this might be or what I can do to get the mpg back up to at least 16??? This is kind of disappointing since the Corsa system is not the cheapest system I could have designed.

Hmm, that definately doesn't seem right. Not sure what to tell you.

your truck has a learning computer.. it may take some time to learn the new exhaust. you may want to disconnect the battery for 5 mins to reset the comp. you may see a differance in MPG.. Good luck

I have had the exhaust on since April 14 and I have also had the battery unhooked overnight last month as I had to put a new starter on. Any other suggestions?

Did you taking the muffler off your truck affect your milage any or was it like that when you bought it?

Did you taking the muffler off your truck affect your milage any or was it like that when you bought it?

I bought the truck new in 2000. This is my third exhaust setup. The first was a Raven system from Midas. I hated it.. really bad reverb in the cab. So I replaced the muffler with a y-pipe. After 4 years. the pipes rusted off and now I have one 4 inch pipe comming out the passenger side before the rear tire. It gives me the sound I have been looking for. I gain maybe an extra mile per gallon from the first exhaust system. I can get about 400miles to the tank hwy and about 320 miles city.
As far as your mpg, your cats maybe bad.. I would have them checked out. or you could have bad o2 sensors.

I will check into my O2 censors. I bought the truck off of a friend with 39,000 miles on it. At the time it had a flowmaster with dual rear exit and I was getting an average of 16.3-16.5 mpg in the city, which was about 380 per tank. I have never really had it on the highway for an extended period of time. When this set up was getting close to falling off, I did some research and several people suggested Corsa for the extra performance and sound. I found a great deal and jumped on it. The sound has been ok, but my performance has been less impressive.:2cents: If I had it to do over, I might check out magnaflow. Anyway I will have my O2 sensors checked soon when I have my injectors cleaned.

That millage is pretty good in the city.. I wish I was getting that. I need to clean my injectors too though.. I have been a little lazy with the maintance on my truck. :)
you may just want to remove the muffler all together.. trust me.. it will sound great.. I promise you will love it!! :D

Has anybody heard what 50 Series Delta Flow flowmasters sound like on the 5.3s???

Little too late for me to be asking now I guess though because my truck (06 Sierra crew cab Z-71) will be gettin one tomorrow, lol.

And since gas mileage was brought up, I've got 21 mpg on a trip, and as good as 18 on short trips, but typicall 17 (computer says 16.7 right now). Pulling that car in my sig I've got as good as 15 mpg and as bad as 14.

Because of the built-in restriction of the mandated catalytic converter, the best smog-legal system in the world, by itself, will not get you more than 1 mpg over stock.

It may sound better, and help the engine live longer because of less backpressure. Just don't expect it to pay for itself several times over with gas savings.

Yes a buddy of mine has the 50 series delta flow on his 5.3L, and he loves it. He has had straight pipes, and some other muffler that was on the truck when he bought it. He likes his 50 series though. I also have the 50 series on a 305 HO and for a car I think it sound good.

Will putting something like a magnaflow catalytic converter help the mpg? I realize that you would have to pay for 2 right off the top.

Yes a buddy of mine has the 50 series delta flow on his 5.3L, and he loves it. He has had straight pipes, and some other muffler that was on the truck when he bought it. He likes his 50 series though. I also have the 50 series on a 305 HO and for a car I think it sound good.

Man it sounds AWESOME on my truck. I was a little torn on what to get, 70 Series Big Block 2, or the 50 series that I have. My other truck (92 K1500, 350) has the 70 series and it sounds really good on it, but I've always wished it would have been a little louder. Well, the 50 series on my new truck is that "little louder", but not too much compared to my old truck, but man they sound awesome.