I have the same catback on my truck and love it. I didn't notice any loss in power or gas mileage when I still had the stock tune, though. It sounded great when the truck was stock and sounds ******* amazing with the LTs and ORY. People compliment me on the sound all the time and setting off car alarms never gets old.

IMO, get whatever YOU want. One of these days I'll get a cutout and do some track testing to see what the Flowmaster is costing me performance wise. It might be nothing, it might be a couple tenths but I won't pretend to know without any data to back it up. Honestly even if I'm losing a couple horsepower I don't care that much, nothing else has the sound I like so far.

 

listen my flowbasterds..they may not make as much power...but they sound facking good

 

I agree, it sounds great, and mine is basically a stocker too, with whatever the dealer put into the PCM (Probably gas mileage crap).

My truck is wierd. Its ultra sensitive to any swaps/changes I make.
I tried doing the backyard mechanic removal of the resonator on the intake, that lots of guys do... my truck wouldnt even go down the road. Lost ALL accelleration, horrible vibration howl that shook the gas pedal.
After the GM garage got their hands on it for the wheel sensor recall, they said they updated the PCM, and its been a quirky dog ever since.

The only thing I guess, if your going to go with Flo's, is make sure if you or whoever installs them, DONT weld on the case!
I also took spraycan high temp exhaust header paint, and coated all of my joints and welds on the outside. It helps to slow the rot down a little bit.

 

after my cam install i replaced my flowmaster with a magnaflow. ive always had flowmasters because of the great sound, but after installing the magnaflow ill never buy anything else. i felt the power increase after installing the magnaflow and it doesnt resonate cruising down the freeway.keep in mind that i have lt headers, no cats and dumped exhaust with a very healthy cam. if i want noise i just open the cutout. i recently got a magnaflow installed on my 96 z71 and also noticed better throttle response on it. if you insist on a flowmaster get the single chamber, it flows better but its really loud.

 

I got a 40 series behind the longtubes and ory dumped in front of my axle. It sounds freggin bad *** if you wand loud! Its got some pop during gear change at wot but i love it. Did i mention there is no carpetpad carpet or center section of my bench in the truck rite now damn its hot

 

If you like the Flowmasters.
look into IMCO mufflers..
they sound like the flowmasters, dont drone as bad, and flow better.
http://www.putfile.com/01thunder

 

I got a flowmaster 40 and it sounds amazing. I have two turn downs at the back bumper. Sounds amazing and only has slight droning at 1.8-2.2krpm...

no noticeable loss in low end power if anything throttle response was smoother. But then again I put my intake on just weeks after the exhaust..

its been said time and time agian that you only lose 2-3hp at most. which can easily be made up else where..