I currently have a 2001 5.3L all boltons 210/218 .584/.584 116Lsa cam and milled .03 862 heads

My exhaust now is pacesetter longtubes, magnaflow high flow cats, x pipe, 2 cut outs, magnaflow muffler has built in x pipe as well. It is 3" true duals besides the x pipe part.

I have been reading 3" exhaust hurts low end tq

Do yall think I would notice any gains if I ran a y pipe and single 3" exhaust over my current set up. I want to get bassani mufflers so now would be the time to change every thing

 

That is a lot of exhaust for a bolt on 5.3. A single 3" would be better. I don't know that it would make a huge difference though.

 

first exhaust set up had shortys and true dual 2.25" out flowmaster super 40
dyno tune 267rwhp 324rwtq

The exhaust now after dyno tune 281rwhp 336 rwtq

14rwhp and 12rwtq was the gain over the 1st exhaust system but the dyno only showed me 3000+rpms so who knows what happened under the curve

I'm most positive these numbers came from the longtubes curious as to what they would have been with single 3" vs dual 3"

 

Where are you from and how important are emmissions? Is your exhaust a mandrel bent system or is it a 'custom' with crimp bends? If I was in your shoes I ditch everything behind the header collectors, pick up a pacesetter Y pipe and a bolt on single 3" exhaust. You will notice the power down low for sure. You may give up a hair right at redline, but thats less noticable than what you will gain down low, especially tip in on the highway with the converter locked. You won't give up much top end, but your curve will look much better. Hell with a legit mandrel bent kit you may even make gains everywhere because exhaust flow will be so much cleaner. It will literally suck the exhaust out of your engine rather than just create havoc like what you have now.

 

Having 2 different X's in the exhaust isn't doing much for you. I doubt it's hurting anything, but if you wanted a truly balanced system, you would see why running an X-pipe can help keep the pipe lengths as close to equal as possible, while still routing the exhaust within the confines of the frame and drivetrain.

I used to have my 2500HD's exhaust dumped straight after my muffler (an X-Pipe Jones muffler), but found a slight boost in midrange power, by extending the length of the drivers side tailpipe (which, due to the X, is the exhaust pulse from the pass.side head) to equal to the pass.side (which is actually the exhaust pulse from the drivers side).

This made them as equal length, as possible, which even made a difference to the smoothness of the tone in the exhaust. It's far from an ideal, balanced system, but it's the best you can do when you have to route both pipes down the pass.side of the truck LOL

It's probably not worth the hassle to change all that, but it's my dumb theory as to how you can potentially get a tiny bit more power out of your setup.

 

I thought the purpose of an X was to eqeualize and combine pressure, and by combining them like that I didnt think you would see benefits the way you did. If it were an H pipe that simple equalizes but does not really combine I could see this working.

I guess I just don't know enough about it in that specific example.

I still stick to my initial suggestion. How high are you revving the 5.3 with that cam?

 

I 80% of the time have the cut outs openand they are located under the rear passenger seat with the x pipe right under the front passenger seat. The drive side pipe from the header has a 45 angle strait to the x-pipe clearing the transmission.

I'll get some pictures tomorrow morning when its bright out.

6000 1st 5900 2nd 5700 3rd

 

Area of a stock 2.75 single (not counting the squished bends) is 5.94 square inches. You're at 14.14 with your duals man..

 

I like the true dual concept with H or X pipe get the pipes to closer to equal pressure. The y pipe design seems to be restrictive at least for the driver side having to take 2 90 degree turns. Does a Y pipe equal out the pressure from exhaust valves to single pipe?

 

I dont think its worth the cost and effort to change it. What are your plans for the truck? I'd save the money and just get a 3000-3200 stall torque converter.