Let's say one put headers on a 2003 5.3 truck and kept the stock muffler. Would that be a total waste? I have converted my single in and out 03 Z71 5.3 to the SS Silverado dual inlet single out let for a 160 CFM increase of flow. Would I still benefit from a set of headers if I kept the SS muffler?

 

Get some Long tubes. But yes, I would think that would give more gain than a catback.

 

I ran my SS with a good sized cam, ASM headers, and no cats for several months on the stock SS muffler. It ran just fine. Actually, it may have run a bit better than it does with my flopro muffler. The best part is that it was quiet and still felt pretty powerful.

 

I had a 97 Z71 5.7 (no headers) and put a Gibson 2 in 1 out cat back on it and lost tons of low end and gas milage. It did however run better up top but at too much cost down low and mpg. It resonated in the cab too. Not as much as others but too much for me. It hit the dirt with in 1 week.

 

I think the biggest myth in automotive performance is that stock mufflers flow like crap. I think they flow okay. And if you want a quiet setup, it really is the only way to go. Unless you are building a 1/4 mile race car and live in the 4000-7000 RPM range, the stocker will do just fine IMO.

 

I noticed quite a bit of power when I had my header system hooked up to the stock cat back, felt just about the same after I had the Magnaflow put in, maybe more high end.

 

I was quite surprised after my B&B duals install. There was no big power increase up top or anything, but I felt a noticeable improvement in low end torque. Not so much a snap in the neck from a dead stop, just the ability to lug up hills with much less effort.

It's probably the 2.125" tubing off the muffler that retains the power for me.

 

Keep it coming guys. I'd like to hear more experiences on this.

 

nativetexan, Broke Huh? Welcome to the club.
When you save up. In my opinion the best cash spent on mine is on the Nelson 93 octane tune with 80% of the Torque Managment removed. It really made it come alive and at least 25 rear wheel HP.
The SS Silverado cat back was a Free-Bee from one of the good folks on the silveradoss.com forum. Monitor the classified section there. Some guys get tired of them taking up space or put them up for best offer. I had to drive 300 miles round trip but I love it. Dead silent, nice tip and a 160 CFM increase in flow over the OE. Don't scrimp and Y-pipe into it. Have them dump your Y-pipe and go true dual into it.

 

not the question at hand, but sorta relates to it. I felt more power after i installed my muffler than with open exhaust.