Hi guys, new to the forums, but not to trucks! Most of my experience is with diesels, I've rebuilt a couple and I know the basics of engines, but I need some advice from someone more experienced about my exhaust. I have an 05 GMC Sierra 5.3 with Volant CAI and blackbear tune, and right now it's stock manifolds and cats, stock muffler replaced with a single cherry bomb glasspack, and duals (2 3/4") straight out the back with 3 1/2" cannon tips. I'm pretty happy with the way it sounds, no popping and slapping like a redneck, just a loud throaty growl at all RPM's. I plan on getting headers, and one day a cam, but it'll be a while before the cam. I think I've decided on these dough thorley headers http://www.summitracing.com/parts/DTE-310Y-DA-C/, unless you guys have some better suggestions (which brings me to my first question, is ceramic better than stainless?). I picked them for the better low to mid rpm power, because i rarely ever put my truck on the track, I just like it to throw me in my seat when I get on it. What I'm really going for here isn't track times or huge HP gain, but efficiency. I want the most bang for my buck with my engine.

Question 1: are those headers considered mid or long tube? either way I plan on deleting the cats, but I need to know the right way to do it so it doesn't cause problems when I get it inspected.

Q2: Will I have to put fake 02 sensors where my cats used to be for it to pass inspection? I know a few people that did this, they had to buy fake o2 sensors off ebay to delete their cats.
Now for the rest of the exhaust

Q3: which would work better for me, a nice corsa cat back system or something custom? I know a great muffler guy that can build me a stainless system. If I do go custom I was planning on an x-pipe with duals straight out the back with some kinda bullets in line.

Q4: If I do go with a custom/ x-pipe system with dual bullets, which bullets are best? I've seen a few clips on youtube of trucks with headers and bassani's, thrush, cherrybombs, etc., but which ones do you guys think is best? I really like the sound of those aero vortecs on the hemi's, but so far I haven't found a clip of them in a GM on youtube. My main worry is that I might end up with drone, I really don't want any drone, just a nice throaty growl similar to what I have now. In fact I've thought about just starting with the headers and cat delete and keeping what I got from there back just to see how it sounds, but my worry with that is the whole backpressure or velocity being unequal from the crossover to the stock muffler location where my single glasspack is now, but all I really know about backpressure is that true duals are bad for a v-8 without an x or h-pipe. I've always heard that can warp valves or something. I read the backpressure myth sticky but all I could gather from that is that what most people refer to as backpressure problems are actually velocity problems. So that brings me to

Q5: Would I be better off to try the headers with what i have first, or just go ahead and do a catback or custom x-pipe dual system?

Again all my experience is with older diesels and tractors, so I don't really know much about the newer computerized enines. Any help is greatly appreciated!

 

I can't answer all of the questions, but the thorley headers are mid length headers and you'll have to get a custom y pipe built. They do make a difference and not a whole lot of guys run them, I love mine.

To pass a visual inspection slot of guys hollow out their cats and leave them on or replace them with a some short bullet mufflers. Once you delete the cats get your tuner to turn off the check engine light and rear O2s.

My cousin has a custom exhaust on his 99 z28 with a 427 and it's awesome. It's basically a copy of Texas speeds rumbler exhaust which is an x- pipe, dynomax bullets with dumps.

 

ive been trying to post of a vid but ive got my self standing it and i dont like it haha try dynatech longtubes with a corsa touring youll love it its not loud at all

 

if i were your, I would wait for the ebay specials to come back up for sale. They are stainless and are like 260ish shipped. They also include a catless y-pipe. for someone like you that isn't into all out performance, the 1 5/8" primaries and 2.5" collectors aren't going to be a big deal. hel they will actually provide better low-end.
Once you put the headers in, your going to need blackbear to retune your truck.

 

Actually, after much debate and a clarification as to how exactly tubing is measured, the primaries are indeed 1-3/4". Collectors are 2.5" like you said, and Y pipe outlet is 3"+...Mine passed the visual test at emissions a few months ago due to those cat-like resonators on the Y pipe.

Regardless, I agree 100% with waiting for the Ebays to pop back up. Mine are 19 months old now and still no complaints with them. Well, I did finally melt a plug wire with my temporary "fix" on that silly driver's side primary, but it took from November 2009 up until last week to do so...

 

Thanks guys, the ebay headers sound good, I like low to mid power more than having my engine redlined. Could somebody post a link?

Oh and I don't have to worry about visual inspection, I know a guy that'll pass anything, its just the computer stuff he can't fake, hell I go up there, he plugs the scanner in, gets the registration and says "come back in half an hour and I'll print it", haha. He says he's got to wait at least 25 mins before he prints it off so the state won't get suspicious, lol.

So I won't have to get fake sensors, just get justin to re-tune it? And also I've heard that removing the cats reduces the gas mileage by making it run rich, I'm assuming the tune would solve this problem?

 

Hell, with the Ebay headers, there's enough O2 bungs on these you can hook all 4 back up, and a wideband.

 

Do you have a sound clip as it sits right now? Does your truck have a resonator after the muffler or is it straight through after your glasspack? How long have you had the Cherry Bomb on the truck? How has it held up? I was thinking about throwing one on my ride to give me the noise to go with the power without spending a fortune just to change sounds.

 

Naw no resonator, just a y-pipe after the glasspack and duals out the back. I like the way it sounds now, not to load but loader than flowmaster or magnaflow, no popping and slapping either. I'll try to post a vid later.

I've got another question, what is the optimum tubing size?

 

2.5-inch dual with an X or 3-inch single after a Y will be plenty. IMHO.