Camin00

I like the cut outs exterior noise but they need to be moved as far back as possible under the bed to eliminate some of the horrible drone they make under the cab.

A lot of people say they like their y pipes and a lot of people say the true dual x pipe is the way to go

I just want to see some dynos and track times to see which set up give more lowend and over all performance.

Mangled03gmc

iTrader: (95)

The cut outs should be as close to the collectors as you can get.

Camin00

I have decided to buy a 2.5" x-pipe and re do the system from the cats back 2.5"
I really do love the true dual idea from day one of getting rid of the stock y pipe.

I'm going to install some 2.5" cut outs later down the road.

Which will give more performance H or X pipes? I dont care about the slight sound difference they make just any lowend and over all performance from the 2

1bdbrd

iTrader: (10)

NA exhaust needs scavaging, not back pressure.

I would get rid of the dual in/out muffler, and get a 3" x pipe appropriately placed followed by 2 smaller 3" mufflers. Then just get rid of the cutouts or at least put them somewhere after the x pipe for better sound.

Camin00

What is scavenging??? all I have ever herd of was back pressure

The cut outs are located after the xpipe right under the passenger seat

The dual inlet/outlet muffler has another x pipe built in to it. It deffinently has more low end with the cut outs closed and more top end with them open.

I designed my truck for tq hp just tags along with everything I do

1st mistake was for this build ^ true dual 3" exhaust 3 years ago. stupid kid decisions

Everything was tolerable till the cam went in a couple of months ago

1bdbrd

iTrader: (10)

An exhaust built with proper scavenging effect, will pull the exhaust gases from the cylinder basically. Back pressure is the opposite basically. Its the effect that opposes exhaust gases as it flows from the combustion chamber. IMO most people equate back pressure with torque because the most common remedy for it is to replace the stock manifolds with a longtube header setup which will make more top end power. Thus the feeling of lost low end.

I still wish I could find the article, because it was very well done. Several years ago (early 2000s), one of the big car mags did an exhaust article covering a custom setup on a built big block corvette I believe. In it they covered how to properly place the crossover/merge pipe and also where to properly place the mufflers if possible. Their result was a car that LOST power when they pulled the exhaust off of it and ran open headers, which was their goal/hypothesis.

I have always been curious how much better a proper x pipe and two good mufflers would be over a single muffler with the x built into it. I can't imagine that flowing as good as standalone pieces.

I do have to ask what size cam and stall you have? That might be where a lot of your lower rpm torque went to.

Mangled03gmc

iTrader: (95)

Yes he is correct as for the scavenging, but in this case I feel that would be a entirely new ball game, could mean a entire new system configuration. To knock on that door, there is a such thing as too much. His cam makes up for some of the scavenging effect over a stocker. Going back to single mufflers but still retaining the X pipe would prob eliminate the drone associated with a big dual in and dual out muffler. So not starting a pissing battle, just saying lol. To have the perfect system, it would be nice to nail the back pressure, scavenging affect, exhaust velocity, but only in a perfect world, hahah

1bdbrd

iTrader: (10)

No worries.

I don't think it would take a ton of reworking though or really any more than he is already talking about. I'd say a simple x to a pair of bassani mufflers would be good enough and not be too terribly expensive if he were to sell off the stuff hes replacing.

Camin00

stock transmission cam is 210/218 .584.584 116lsa this cam makes more tq/power everywhere 1100rpms and up verses the stock cam.

I had to run the headers open one weekend till the shop opened up monday to do the exhaust system. The truck was terrible, so much slower and just stupid loud.

I'm assuming it is better for the x pipe to be as close to the motor/headers as possible? equalize the pressure as soon as possible.

From what most people say true dual 2.5" x pipe possibly makes a lil more power than y pipe 3-4inch?

Mangled03gmc

iTrader: (95)

I think that it will be little to no difference in your particular case as far as feeling more power or tq vs a single or true duals. Like I said, I would put the C/O's as close to the collectors as you can get, then the X pipe. Me and 1BD are pretty much on the same page, as far as the drone. Most cases again the big muffler with 2 in 2 out is doing it. With open headers the truck will tend to run bad, because the o2's are so close to the end of the collectors, will get some fresh air that reverts back into the collector. This will be picked up by the o2's and give the PCM a lean code, the PCM will dump fuel to the engine to correct it. I think you should do the single mufflers ( true- dual) and then have the PCM tweaked a little bit. Should be able to tell a difference in sound/drone and prob get your low end back with the PCM flashed again. I am no expert on this, but have a good idea about how it works. LOL