I've been searching but I need specifics...
 

So I just bought my 2013 GMC Sierra CC/SB 5.3 about a month ago. I like it but I'm sure you all know it's a little slow and the mpg can definitely be better. So I've been looking all over this site for a specific answer to my questions and I just can't find an exact answer to what I'm looking for. So I'm just going bolt on's. (For now until my warranty is gone). I think I've settled on TSP long tubes and most likely the SLP catback. I've read a lot about CAI's not being worth the money, is that true? I was gonna go Volant but I'd rather save $300 if I could. I already got a K&N drop in for free so I'm not sure what to do there. My biggest issue is cats. I want to stay legal for Texas and I'm not trying to wake the neighborhood when I leave for work in the morning. So what is the cheapest way to put cats in this set up? Buy hi-flow cats and have them welded into an off-road y-pipe? Will I need anything that isn't necessarily well known? Like O2 extensions? Heat shields? Are there any little misc. things that might pop up with this set up that I should know about before my truck is in pieces and I'm stranded? Thank you very much for any and all replies.....

Oh and I certainly will be getting a tune once this is all done. Any recommendations in the Houston area?

once ur truck is tuned u should still be able to pass emissions, even without the cats. if u want to keep ur cats u can get a midpipe or you can cut your cats to make them free flowing, but to someone looking at ur exhaust system you will still have cats. if u have a k&n drop in filter you can get a MIT (modular intake tube) that will go from ur throttle body to stock airbox. as far as warranty goes, if u remove your cats and rear O2s i would imagine that your emissions system will be void under warranty because you are removing components from it. they could even go as far as voiding your powertrain warranty as well. just do some research and talk to gm for specifics on warranty coverage.

If I went without cats or did what you suggested would I lose a lot of my low end?

your truck has three cats. i went with kooks longtubes with catted y pipe and got rid of the third cat. you will not pass emissions with no cats.

That's exactly what I'm thinking but Kooks are kinda expensive for me. Do they sell the catted y-pipe separate and if so do you think it will match up with what I plan on getting? (SLP catback and TSP LT's)

are you talking about an inspector just looking to see if the vehicle has cats or an actual smog test? idk, never had an actual smog test done, just a visual inspection, that was in missouri anyways. never had any type of inspection in kansas.

No, you would be freeing up more exhaust flow, it should make it even more torquey. When i did everything to mine i also did a cam swap but i put it a mid/top end range cam, but i still have the same (as far as the "seat-o-meter" goes) low end torque...at least as compared to stock. idk, ur truck is 10 years newer too lol. doesnt it have that active torque and fuel management?

Is your emmissions a sniffer or visual inspection, or just a plug into the OBDII port to check for any codes? If its just checkign for codes then you wont have an issue.

As far as bolt on mods go, the only one that will have a positive effect on mileage will be the tune. The mods you are talking about making will definitely increase air flow and power... but with an increase in airflow there is also an increase in fuel consumption. The truck does what it can to maintain a steady air fuel ratio, and with more air passing through it needs more fuel too.

That being said if it were mine and you just want a little more giddy up I would go with some stainless LT's and a single bolt on 3" cat back with the intake tube (your air box is actually pretty good) and a tune. If you want more than that go straight for boost.

A maggie makes for a great DD power adder. Throw 8# at it with the mods above and it would feel like a new animal... only thing I may change is a 3.5" cat back at that point.

Emissions testing? In texas? They just check to make sure your lights, horn and wiper work here in San Anto.

Certain counties are noncompliance counties according to the EPA so they do emissions testing. El Paso is just a plug up to the computer and check for codes and status testing. Not sure how rough other parts of Texas get. Where I'm from, it's lights, brakes and forget just about everything else lol.