Custom Exhaust - 986 Forum - The Community for Porsche Boxster & Cayman Owners

yellowboxster01 · 08-17-2009, 09:09 AM

Well I have the Stebro Race exhaust and it's just too loud for my liking. I kicked around the idea of buying a new exhaust but, don't think it would be that difficult to make one.

My idea is getting two Flowmaster or Magnaflow universal mufflers with 2" in and 2" out. Then get some mandrel bent pipe and weld it together. It doesn't seem like it would be that complex especially looking at the current muffler I've got. While I'm at it, I'd like to make some mandrel bent bypass pipes. I have a friend with a mandrel pipe bender so, that takes care of that.

How much am I looking at in piping material, such as the cost of the correct grade of steel piping for an exhaust?

The mufflers are around $75 each.

BYprodriver · 08-17-2009, 09:33 AM

mild steel tubing cost is minimal, try McMaster-Carr if you don't have a local source for all your fabrication materials

23109VC · 08-17-2009, 02:45 PM

would it sound very good? given that so many of the aftermarket units drone...you would run the risk of spending the $ to make it, only to find that what you custom made is also too loud???

Boxtaboy · 08-17-2009, 03:12 PM

Both these guys fabricated an exhaust from Magnaflow mufflers...

http://986forum.com/forums/showthread.php?t=15541&highlight=magnaflow

http://986forum.com/forums/showthread.php?t=5175&highlight=magnaflow

yellowboxster01 · 08-17-2009, 03:57 PM

Quote:

Originally Posted by 23109VC

would it sound very good? given that so many of the aftermarket units drone...you would run the risk of spending the $ to make it, only to find that what you custom made is also too loud???

Flowmaster 50 series mufflers are what I've decided on. It's a 3 chamber design and after reading reviews, there is little to no resonance in car. I'm going to go 2.25" from the headers all the way out. I was thinking about putting resonators in the cat bypass pipes like the Fabspeed 986 exhaust but, I'm not thinking it will be needed with the 50 series.

Can't be more than about $400 to make one. All the welding will be done by myself. If nothing else it will be kind of fun, I'll run it with pride. haha

Thanks for the thread links.

j.fro · 08-17-2009, 05:12 PM

I've been thinking of making a muffler as well. After you've built the Flowmaster setup, how about weighing it vs the stocker.

70Sixter · 08-18-2009, 10:30 AM

I hope you can do it without too much loss of power and highway droning. Matching exhaust backpressure and timed pulses for max power is very hard to do. With some decent arithmetic you can probably get close to equal length exhaust paths Especially for the street.

Weight of the exhaust is secondary to engine performance.

I saw one guy spent $20k for a custom new CGT exhaust that sounded better to him, but produced net zero hp or torque.

I'd try Pedro's muffler mod first.

yellowboxster01 · 08-18-2009, 10:32 AM

Quote:

Originally Posted by j.fro

I've been thinking of making a muffler as well. After you've built the Flowmaster setup, how about weighing it vs the stocker.

I know the stock muffler on my 2.7L weighs in at right around 47lbs is I remember correctly. I put the stock vs. Stebro race on the scale during my installation. I have it all recorded somewhere but, the Stebro was right around 14lbs.

That's another thing that I "can't lose" on is weight loss. The setup I'm going to build will still be lighter than stock. I like the quietness of the stock muffler but, the weight is a huge disadvantage especially on the track.

Boxtaboy · 08-18-2009, 10:38 AM

Quote:

Originally Posted by yellowboxster01

I know the stock muffler on my 2.7L weighs in at right around 47lbs is I remember correctly. I put the stock vs. Stebro race on the scale during my installation. I have it all recorded somewhere but, the Stebro was right around 14lbs.

That's another thing that I "can't lose" on is weight loss. The setup I'm going to build will still be lighter than stock. I like the quietness of the stock muffler but, the weight is a huge disadvantage especially on the track.

FWIW, when I put my Dansk exhaust on, I weighed my OEM 2001 muffler after I took it off, and it weighed in at 28 lbs. That was just the muffler, and no connections/clamps. If you like the character of the stock muffler, I would try to find a used stock OEM 2003/4 muffler. They have a nicer growl down low than the pre-03 ones, and have no droning issues.

yellowboxster01 · 08-18-2009, 11:49 AM

Quote:

Originally Posted by Boxtaboy

FWIW, when I put my Dansk exhaust on, I weighed my OEM 2001 muffler after I took it off, and it weighed in at 28 lbs. That was just the muffler, and no connections/clamps. If you like the character of the stock muffler, I would try to find a used stock OEM 2003/4 muffler. They have a nicer growl down low than the pre-03 ones, and have no droning issues.

I feel stupid, my weight comparison was with the stock cats also.

The Stebro muffler alone is something like 14-16lbs.

chaudanova · 08-18-2009, 03:17 PM

Yellowboxster, would you please record/post some sound clips/video of the Stebro race muffler & bypass pipes setup?

I'd love to hear that combo... I currently have the Stebro race on as well, and was wondering how it would sound with the bypass pipes...

Thanks in advance!

yellowboxster01 · 08-22-2009, 11:17 AM

Quote:

Originally Posted by chaudanova

Yellowboxster, would you please record/post some sound clips/video of the Stebro race muffler & bypass pipes setup?

I'd love to hear that combo... I currently have the Stebro race on as well, and was wondering how it would sound with the bypass pipes...

Thanks in advance!

Yeah, I will record some video this weekend.

chaudanova · 08-24-2009, 05:34 PM

Quote:

Originally Posted by yellowboxster01

Yeah, I will record some video this weekend.

Sweet!! Any updates? I'm very close to just throwing them on!!

chaudanova · 08-27-2009, 09:40 PM

Any updates? How do you like the sound with the bypass pipes, in conjunction with the stebro race exhaust?

I've had the stebro race setup for awhile now and have loved it... Just tonight, I decided to try it out with the bypass pipes... I'm not sure how I feel about it yet...

Sitting and revving, it makes a great sound.... I've only driven a few miles so far with the new setup.. It is LOUD... Not sure how much I like the sound at lower RPMs right now, and driving normally around town... When I romp on it aggressively, the sound is awesome... Still debating if I like it overall or not....

23109VC · 08-28-2009, 06:06 AM

what's the difference between 03-04 mufflers and the pre03 mufflers? why are they different sounding??

blackbox · 09-15-2009, 05:46 PM

I, like so many others here built my own exhaust system. I basically copied a stebro race setup, but i used aluminized 2" steel.

The sound is identical (to my ears) to all the stebro clips that I've heard. The sound is awesome. Of course I got the "drone", but I also got a faster throttle response (which I love). I haven't had a chance to dyno it yet because the only local shop with a dyno has computer software/hardware problems. Hopefully they will be up and running soon.

My understanding of the drone problem is pipe length (engine vibration causing the pipes to resonate at a particular frequency based on pipe length) and lack of acoustic baffling to combat the first problem.

Would a tip insert style baffle (like the harley guys use) do anything to help with the problem, or would it only lower the decibel level? It might just move the drone to a different rpm range.

I'm just thinking out loud I guess. I've only got $200 bucks in this project, but I would really like to keep it installed. any ideas?

Cloudsurfer · 09-15-2009, 08:54 PM

03-04 mufflers sound a bit deeper, and also have provisions for mounting different tips.

As to getting rid of the drone on your exhaust, I don't think you're going to get a drone-free exhaust by utilizing that type of design. For what it's worth, I have the dual muffler FabSpeed setup, and it sounds amazing and is drone free.

23109VC · 09-16-2009, 08:37 AM

i'm curious if the "maxspeed" system out there is essentially a knock off of the fabspeed system and is truly the same thing?

the sound clip video they have on their website / youtube sounds cool.

i also heard a sound clip in youtube of a base 2.7 wth a RUF exhaust and it wsa AMAZING sounding.. but I haven't seen anyone selling a RUF exhaust for our cars.

ddb · 09-16-2009, 02:02 PM

I've driven my 2.7 with the complete Maxspeed system now for 600 + miles. Honestly, I haven't thought about drone at all because it just isn't an issue. If there is some drone, it definitely isn't offensive. The description of the system from Maxpseed is accurate.

BTW, no CEL issues at all (knocking on wood)!

ddb

blackbox · 09-16-2009, 04:14 PM

I found out thru internet searching that Ford Mustangs encounter the exact same problems when using particular Magnaflow and Flowmaster cat-back systems. They also get resonance around 2krpm.

One mustang board member( http://forums.corral.net/forums/showthread.php?t=496793) solved his drone problem by adding a 1/4 wave closed-end resonator tube before his muffler. The closed end tube is reflecting the the sound wave back into the exhaust path out of phase, thus cancelling the resonance. Sounds simple enough, but I'm not sure I could apply it to my setup.

One of the board members also posted a link to an aftermarket BMW exhaust that incorporated the same style of resonator tube. Check out the link above. It was a pretty interesting read.

I've heard the Fabspeed and Maxspeed exhaust. They sound good, but not my taste. I like a less baffled sound.