Rebuilding the DF exhaust system

Rttoys

Goblin Guru
I’m going to say the stock exhaust and the flow master I replaced it with are gonna be close to the same db, just a lower tone with the flow master. The straight pipe one I built would still be the 6 or so db louder than “stock”. The straight one is pretty near straight through, so it’s loud with a little tone. Even with the “db killer” installed, it doesn’t do much. Sounds good though.

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mike_sno

Goblin Guru
I’m going to say the stock exhaust and the flow master I replaced it with are gonna be close to the same db, just a lower tone with the flow master. The straight pipe one I built would still be the 6 or so db louder than “stock”. The straight one is pretty near straight through, so it’s loud with a little tone. Even with the “db killer” installed, it doesn’t do much. Sounds good though.

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Ok, thanks. I was wondering if I should test the just straight one too. I ordered everything in3in a flow master to install where the cat was https://www.flowmastermufflers.com/products/exhaust/mufflers/flowfx_mufflers/parts/71419 and another for the stock https://www.flowmastermufflers.com/products/exhaust/mufflers/flowfx_mufflers/parts/71229

I just underestimated the 3in 180deg radius and the weight of that complete exhaust.
 

Rttoys

Goblin Guru
It becomes a very delicate balance on all fronts with that. Straight shot flange to muller, 3” is the easiest and most direct route. Bending and turning like Df did, you might want to step down to 2 1/2” to make it easier to deal with and not be so big and heavy.

that’s why I just cut and spliced a new muffler into the Df setup. It was the easiest route, without reinventing everything. I also wanted one like my old experimental motorcycle muffler one, so I made the straight one again. Gotta have options :D
 

mike_sno

Goblin Guru
It's done. Noticeable louder! It sounds like my Goblin is now grown up. LOL. I would say it's as loud as those Ford Mustang with loud exhausts. Definitely louder than I like it to be, but it also sounds quite cool! Feels like a lot faster, but not sure if it really is.

I tried it during building with just 1 exhaust like in picture 2, but that was even during idle to loud. This set up is up to 3k rpm moderate, but under WOT it is LOUD.

Have to get a DB killer or something. I still have the other exhaust, so I have a quite option for the street and a loud for the track, where its allowed.

Bracket to be build...

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mike_sno

Goblin Guru
@Rttoys Does the DB killer cone take the noise down noticeable?


I also wonder if I should have cut the last 90 deg pipe on an angle to reduce the noise ?!?
 

mike_sno

Goblin Guru
Well, it's also subjectively. Going from stock exhaust with catalytic converter to 2x basically a straight exhaust. I was surprised that even in idle there is quite a bit of flow coming out of the exhaust. I was for whatever reason expecting almost no flow.

It's not as loud as the engine was without the plexiglass behind the seats. And it's also not that uncomfortable as the intake noise. Overall it sounds really solid, but a bit to loud for me under WOT.
 

mike_sno

Goblin Guru
Parts used to build a 3in Stainless Steel Exhaust:
https://amzn.to/47qjs04 JY PERFORMANCE 3 Inch Universal T304 Stainless Steel Exhaust Pipe Tubing Kit 16 approx. $125,-
https://amzn.to/3B2tyZ3 2 Pairs O2 Sensor Bung Universal Stainless approx. $13
https://amzn.to/3ZsGD86 Stainless Steel TIG Welding Rods ER308L 1/16" x 36" (1 Lb) approx. $22
https://amzn.to/3zs7tm8 ZZP 3in LSJ Flange approx. $38
https://amzn.to/3Tuir1u Flowmaster FlowFX 71419 approx. $51
https://amzn.to/3Xug2ow Flowmaster FlowFX 71229 approx $51

Material approx $300 + 1/2 day welding.

Will get a weight of the exhaust when I take if off next time.

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