Just curious of opinions on a NNBS 6.2 stock catback on a stock 5.3. Do you think I'll lose any torque with the increase in catback diameter slowing down the exhaust velocity? What about on a 6.0?

Yes, I asked about this a year or so ago and yes I'm bringing it back up for more discussion. Thanks for opinions and any experiences.

 

I don't think you'd really notice any significant difference.

 

On a stock 5.3 I think you might notice a little torque loss down low, but maybe not if the muffler supplier adequate backpressure? I'm not sure how restrictive the factory 6.2 muffler is?

 

Back pressure is a myth, pretty much every vehicle runs less than 1-3psi of back pressure on a NA engine.

He still have the stock y-pipe and 3 cat converters so whatever comes after them pretty much doesn't matter.

 

not relevant to your question but what part of KC you in? Overland Park here.

 

Im using Speed Engineering True Dual 3in and its perfect.

The most restitive part of yout exhaust is your manifolds and Cats. Anything after them is just noise...

 

Well that is part of the conversation too... I have Thorley Tri-y's going on also. I know people say the small primaries suck, but that's what I have for now. Not installed yet, but the idea is that they will help with low/mid range torque.
Also, I want a quiet setup, so a stock muffler may get me that. Does the 6.2 muffler flow better than the 5.3?

I'm in Lenexa, near Oak Park Mall, basically OP. And I wish I was Area47 tuned!

 

What engine set-up did you put the true duals on? Did you notice a bump in power? Any loss down low?

 

I ran a 6.2 stock catback on my 2011 5.3/6spd. Dynoed 315 tune and catback only with a K&n drop in filter. Stock y and cats. I did this swap literally the first day from picking the truck up from the dealer...

 

That seems convincing!