Exhaust advice needed

[RichLV]

Hi Guys.

Question for those of you who have made a custom exhaust system for your cars. Doesn't matter if it's a B4 or a C4.

I'm doing an exhaust rebuild soon, to accomodate the 7200 turbo and going for a full stainless turboback 3 inch exhaust. It's going to be a straight pipe up until the end. At the end is what I cannot decide what to do. I'd like very much to keep the 2 exhaust pipe layout which fit right under the cut of the rear bumper, pretty much only for aesthetic reasons. Now the problem is that there are not any readily available back mufflers with 76mm inlet and 2x 76mm outlets. Because of that I'm most likely opting for a Magnaflow muffler with single 76mm inlet and single 100mm outlet. But it's possible to fit a Magnaflow resonator and just weld the outlets to it as I like.

So the question is, what would be better for maximum freeflowing exhaust, a single muffler or a single resonator? I'd like to make it once and leave it. Also, would a 76mm inlet and 2x 76mm outlet configuration work?

This is the muffler in question (or any similar ones) - http://adparts.eu/lv/auto/exhaust-sy...ies-14835.html

Here's a bunch of resonators - http://adparts.eu/lv/auto/exhaust-sy...76mm_3_00.html

This is what I have now -

[ringbearer]

Leave the stock rear muffler?

[RichLV]

Exhaust advice needed

I don't have it. And frankly I don't like it much.



This is how mine looks. I'd like to keep it this way if possible. But I can't use this muffler, inlet is 60mm and it's a bit too loud.

[UrS4boy]

All I will say is:

1. if you don't put a centre muffler/resonator in there the drone on the highway will kill you or it will kill your girlfriend/wife and she will kill you. Lots of BTDTs where people *think* that they can get away without a center muffler and then find out about the drone.

2. The Stromung systems that we like over here a) use a center muffler/resonator and b) quite sure they end in two exit Magnaflow. All 3" (76 mm)

http://www.stromungexhaust.com/92-955-s4-s6-ur-quattro.html

Stromung sound: https://www.youtube.com/watch?v=zBZ_wug7B6g

[RichLV]

Fair point. How does it flow in that configuration (resonator + muffler)?

Looks and sounds great. The cost though. How big are the tailpipes at the very end? 2x76mm?

Would be nice to get that authentic 5-pot turbo sound. My current muffler fakes it in a way it sounds a bit like a diesel 5-pot. :/

Is it ok, if I for example would get a following end muffler:
http://adparts.eu/lv/auto/exhaust-sy...ies-14815.html
and re-weld it's 57mm inlet to a 76mm inlet?

[jeffstoo]

Hi
I have just made a 3" turbo back exhaust for my s2 coupe. I have used 2 silencers, the back one has 1x 76mm inlet and 2x 63mm outlets. Sounds good when stationary but I can't comment on drone/loudness as I haven't driven it yet. Be prepared to use lots of bends, also it's a tight fit over the rear driveshaft.

[UrS4boy]

Fair point. How does it flow in that configuration (resonator + muffler)? Looks and sounds great. The cost though.

Sorry but you probably don't have enough money to max out the potential of that Stromung exhaust. The stock exhaust is good for 400 hp, the Stromung is good for well over 600 hp based on that car in the Youtube video - which was making well over 600 hp crank.

I wasn't suggesting that you buy the Stromung system but to use it as a guide in constructing your own.

Here are a couple of MagnaFlow Example final mufflers:

https://www.magnaflow.com/products?partNumber=14815

https://www.magnaflow.com/products?partNumber=14803

[montyrs2]

Hi
I have just made a 3" turbo back exhaust for my s2 coupe. I have used 2 silencers, the back one has 1x 76mm inlet and 2x 63mm outlets. Sounds good when stationary but I can't comment on drone/loudness as I haven't driven it yet. Be prepared to use lots of bends, also it's a tight fit over the rear driveshaft.

Which boxes did you use mate? Just about to start building mine and looking at options. Do you have any pictures?

Cheers

[RichLV]

Sorry but you probably don't have enough money to max out the potential of that Stromung exhaust. The stock exhaust is good for 400 hp, the Stromung is good for well over 600 hp based on that car in the Youtube video - which was making well over 600 hp crank.

I wasn't suggesting that you buy the Stromung system but to use it as a guide in constructing your own.

Here are a couple of MagnaFlow Example final mufflers:

https://www.magnaflow.com/products?partNumber=14815

https://www.magnaflow.com/products?partNumber=14803

What makes you think that?

All of these dual outlet mufflers have a small inlet. :/ Probably will use 2 universal mufflers and just fabricate the outlets as needed.

[Rusty]

I have no centre and it's silent on the motorway. The keys to success are to have a change in size ~half way along, so start at 3" and drop to 2.75" just ahead of the rear axle and to have the exhaust supported in as many places as is practical.

I have 2x 2.5" straight cut and it looks near stock. Car runs the same setup you have and the exhaust is not an issue. By the time the gas gets to the rear, it's cooled a bit, so the smaller pipe isn't an issue.

[jeffstoo]

Which boxes did you use mate? Just about to start building mine and looking at options. Do you have any pictures?

Cheers

Hi Monty
I used 200x100x300mm long oval, centre/offset for middle box. After fitting I think maybe an offset/parallel would be a better option. For the back box I used a 200x100x360mm oval, 75mm centre inlet/ 2x 63mm outlets. Can't do 75mm outlets as the box is too small. I sourced the boxes from here http://www.304stainlessexhaustparts.com/. I think Jetex do the same size, or similar boxes but they are not weld on. I don't have any pictures of fitted exhaust but will be getting an MOT soon so could take some if you want. A few random pics. HTH