BASELINE

I am totally unbiased on this subject as I have neither setup, but have been toying around with BOTH ideas for some time. Summer is approaching and I'll be doing something soon. I'm open to both concepts....so here are some more thoughts.

Magnaflow has a few different dual in/out mufflers in a 2.5 inch config. They have one where the center of the outlets sit only 4 inches apart, if you were to go with 3.5 inch tips out back like the ASP Tru-dual, they would sit exactly .5 inches apart if you welded them straight on. Or you could bring them in 1/8 of an inch each for a .25inch gap....thats not bad!! That same muffler is only 5inches tall, I highly doubt it would cause any additional clearance issues.

I 100% agree with you on the 3.5inch single piping being easier to make a straighter system out of. And that is a pretty important thing to consider. However, I'm not buying the vacuum theory of dual 3 inch downpipes merging into a 3.5inch tube creating a vacuum, I think it would still cause turbulence as you are collecting gas flow from two separate sources into one source with a smaller overall cross sectional area.

I'm afraid i can't speak to the ability of the single 3.5inch pipe having a better thermodynamic capability of retaining the exhaust gas temperature high vs. that of a dual 2.5inch setup. I don't have an engineering degree, so i don't want to talk out of my ***. However my first thought is that it would be the other way around, but that initial impression could be flawed. If i thought of a large diameter hose of hot water vs. two smaller ones...I can see how the larger hose would maintain the water at higher temps longer than the two smaller ones. If the same fluid dynamic priciple applies to air, then you have a valid point.

One more thing I thought of, which is not as big of an issue is that of running an exhaust setup that is entirely divorced all the way back from a sound perspective. The separate banks would run as 2 individual 3 cylinder engines firing together. Dodge ran into a similar problem with the Viper and their sidepipe exhaust system. If I recall correctly they had each 5 cylinder bank running entirely divorced which made the car sound more high pitched and not as burly as a V10 should, it was then corrected with an X or H pipe, I don't recall. So I could see how the Single pipe might have a deeper sound due not only the merged exhaust pulses of all 6 cylinders but also due to the larger diameter tubing itself.

I am curious to know how much Muffling it would take to get a 3.5inch exhaust down in db volume to make it tame on the street. With the rear case being removable for days when clients, girlfriends, neighbors, and civility don't matter and you just want to hear the car untamed.

TwentyValveB5+S4

FWIW, my dual 2.5" has an x-pipe towards the rear.

BASELINE

why?

TwentyValveB5+S4

I forget the reason Brent (Labree) said he put it in there. I know part of it was to fit through a certain opening, but there were some other benefits too that I'm forgetting.

BASELINE

Just talked to him....Brent is a great guy too!!

TwentyValveB5+S4

did he say why it isn't in production yet?

BASELINE

He said it is a low volume item and doesn't yet warrant production. Maybe in the near future when more youngin's get their hands on B5s for modifications.

But we talked about putting a kit together that would allow me to work with my welder to put something together. He could send me pre-bent pipes and I could fab the rest here on the east coast.

Very nice guy though.....


What was your experience dealing with him?

TwentyValveB5+S4

picked it up two weeks later with DPs and this dual 2.5" on the car. very happy with the results.

One thing I will say is that Brent will talk your ear off if you let him!

However, the O2 wires were not properly secured, causing one to rub on a DP and burn through, shorting the O2 and my ECU

twinturbofun

Do you have any video's of your exhaust by now?