Which exhaust is better for performance, a single muffler or true duals with an X pipe and factory cats. Also which is the best pipe size for each? I plan on exiting the pipes right before the passenger front tire. I am planning on using either Magnaflows or possibly PVmufflers. Also, those with duals have any problems with SES lights? Any opions would be great.

This my first mod to the truck. Mods planned in order:
Dual Alt with batteries
Electric fans with low thermostat
Dual air intake
Programmer
Headers

 

It kinda depends on what you plan on or are currently running. I've got the stock exhaust with a replacement Flowmaster and it works just fine. If you plan on going with headers then I would go with the true dual exhaust. A 2.5 pipe would be good enough for about 450 hp. If I'm wrong about that then someone please correct me. I can't see the ses light being a problem if the exhaust setup is right.

 

From my research, I've heard that true duals will sap some of your end torque until you go boosted. I ended up going with a Corsa catback and no regrets here. The only SES problem will will encounter are if you go with uncoated long/mid headers and removal of the cats without using o2 sims or deleting the emissions with LS1edit or a custom PCM.

With the factory cats in place you shouldn't lose too much backpressure; therefore, maintaining most of your low end. It all comes down to personal preference.

 

I just went from a single exhaust, granded it was a stock system from a Silverado SS to an almost true dual system. I say almost because I have about a 16" length of single 3" pipe connected to the stock Y after the cats to a Magnaflow Y pipe. Then two pipes into two Dynomax Superturbo mufflers and dual pipes out to the back. I consider the single 16" section a real long X pipe, I didn't want to cut off the factory Y because if I didn't like it, I would be stuck with it or have to buy another Y pipe set up which I've seen people asking if anyone was selling one. So it's almost true duals. I used 2.25" pipe, 2.5 is to big in my opinion and that's why I think some lose low end. I didn't lose any low end and it really pulls on the top end now. If you stay with 2.25" pipe, I think you should be ok but someone can chime in if I'm wrong.
Jim