Ok, just like the title says...I am running a Gen 1 383 that I am going to be hooking up a single 3" running out the back. So I am going to put a magnaflow y pipe connecting the cat back to the headers. So, my question is dual 2.5" to the y or dual 3" to the y? And why you think that?

I was thinking 2.5 for velocity but I have SS mandrel bend in 3" sitting at my house so...it is throwing for a loop. I have true duals now but going for a more conversative approach on the street. I plan to add a cut out just after the y pipe. Thanks for your suggestions.

 

any opinions/suggestions?

 

ttt......

 

This makes sense to me. Dual 3" sounds pretty big for a street truck. However since you're taking it down to a 3" anyway it may not matter as much. Maybe a larger pipe after the Y would be more appropriate. What kind of HP is your engine making? Maybe we'll get some input from an exhaust guru.

 

about 450 fwhp but i plan on 520 fwhp soon and then add a bottle.

 

In that case I think 3" off the headers would be warranted but I would be afraid that you might be choking an engine pushing almost 700hp through one 3" muffler and pipe in the future.

 

yea...but i will have a cutout so...I'm not too worried about that. Just going for a quieter sound during daily driving and open the cutout at the track.

 

True but you said your cutout would be after the Y so you would be squeezing it through the smaller pipe briefly before the cutout. How about dual cutouts before the Y?

 

possibly but don't know yet. I just talked to bluecajun about his exhaust....he has the same setup on his 5.3 that I am thinking about so I think I might so that way.

 

I have dual 3" into a 2x3" to 1x3.5" Flowmaster Y followed by a 3.5" cutout then necks down to a single 3" magnaflow out to the stock exit location on my H/C LS1 and it does great. I had this exhaust initially on my h/c 5.3 w/100 shot and the cutout open was a little much for it. I havn't done a full test cutout vs full exhaust on the LS1 yet though.