Coupe Exhaust Options

[LateApex]

Just a poll ...

What exhaust pipes have you settled on in your coupe build?

I expect a lot of "Boig" responses, and more than a few "stock" FFR twin pipes. Anything else? Do, for example Roadster pipes mate with the Coupe SBF ball-flange headers?

I have been spending too much time on a hack to reduce exhaust noise on my coupe ...

Thx in advance for any feedback !!

[UpNorth]

Stock FFR with ceramic coating in white for me.

Francois

[Rsnake]

I have made 4 exhaust systems for the coupe looking for the right sound and look.
I think the ones in the video I made are near perfect.
https://youtu.be/6cDpWwb-Yfc?si=d4r_rizq0lCGl8ca
You still need hearing protection when driving but most of that is tire noise as 200 TW tires for autocross are noisy as hell.

[Rian_Colorado]

I'm surprised no one has said Gasn yet - I've always thought you should check those out Bob - no ball fitting (direct bolt on) and at least somewhat more quite according to several folks....

Rian

[David Williamson]

I have Boig single pipes ceramic coated. I think the choice if you are going to change from the FFR pipes is do you want single or dual pipes? Single is Boig dual is Gasn. Also the engine type and cam makes big differencee in the sound.
David W

[edwardb]

Very happy with the Gas-N's on mine. Having dual pipes was a must for me. At the time I built mine, Factory Five only had the bare steel version. They were "Nascar loud" and at least mine very poorly welded. My Gas-N's aren't super quiet. But the best option at the time for how I envisioned the completed build. But then the Coupe isn't very quiet no matter what. We wear ear protection and just drive it. The polished SS pipes that Factory Five offers now look good but I have no experience with them.

[lewma]

Stock FFR ceramic coat black

[Dave Tabor]

FFR stainless. You have to wear ear plugs no matter what the sidepipes anyway.

Dave
Gen III #17

[LateApex]

Rian, I agree that if I were to do this again, I would lean to the Gas-N-Pipes. As Paul notes, the twins are very attractive on the Coupe and they minimize snake bite. The FFR stainless pipes are reasonably well finished, but the mirror-finish of the Gas-N's is outstanding.

As I may have mentioned in the past, I purchased the FFR pipes and ball-flange headers with my kit. I quickly realized that these are indeed NASCAR loud, and regardless of my wearing hearing protection, too loud for my taste. So I started digging into the pipes and playing with baffles. Cutting off the turn-outs was the no-turn-around point.

When one does get to peer inside the side-pipes, it is easy to see why these pipes are so loud. No baffling and very small perforations in the belly walls. I tried the Car Chemistry inserts - don't waste your time here. I also tried Vortex cones. These likely do help the flow be more laminar, but there is no significant decibel reduction.

Next, I secured some full-length "HighFlo Performance" baffles. Installing these is a bit of a trick, as part of the installation involved wrapping the baffle with ceramic cloth. Actually it involved inserting the ceramic cloth into the belly of the side pipes and then sliding the baffles home. The second time I assembled this, I used a ceramic cloth with an embedded very fine wire. Without wire, packing will eventually (or not-so eventually) blow out. The sound reduction is decent and the pipes have a nice tone.

And then I started developing a rattle - this is the baffles rattling at the head end. I had riveted the baffles at the rear where I had cut off the turn-outs. After riveting, the turnouts were re-attached using set of Borla clamps. To fix the rattle, I have moved to 1/4" SS blind rivets with the correct grip range and a tensile strength of 2000+ pounds, and some SS strips wrapped (and secured) around the tail of the baffles that result in a snug fit, i.e.: no gap between baffle o.d. and the i.d of the side pipes. I had to do a little grinding on the domed head of the rivets to seat the Borla clamps properly. Results are good so far. I'll get a few hundred more heat cycles on the system before I declare success.

I have also commented on the ball flanges. Not a fan of that design. They do not tighten up well, and are a hack IMO. IF I had purchased a set of headers with a shamrock flange, THEN I would have bought the Gas-N side-pipes. IF my latest kludge doesn't perform well, THEN I'll likely purchase a set of pipes and headers from Gas-N, and hang my existing system on the wall as a testament to "Good Engineers Gone Bad" ;-). To tell you the truth, I never thought to become an exhaust engineer - Haha!

[Indy Shu]

LateApex,
FYI, the headers that i got from Gas-N do have a ball type connection similar to FFR. Has a wrap around band instead of the 3 bolt set-up. Not ideal because as you mentioned they are hard to seal up, and the O2 sensor is just after the connection. The adjustability is nice though.

[David Williamson]

The reasons i switched to the Boig pipes are. The original pipes from FFR were so loud that even with ear plugs my ears were ringing after a 30 min ride and I planned to do long trips with the car. I have enough hearing issues that I did not want to make it worse. I would have liked to keep the look of the dual pipes but at the time Gasn had not done Coupe pipes so .... Boig it was..
Note that my Coupe is #16 from early 2017 - I ordered it late January so some changes to the pipes might have been made since then.
David W

[LateApex]

It has been awhile, so I thought an update was in order :-)

I received my GasN pipes in a couple of stages just recently, and have installed them. A couple of observations:

• Working with Georgie Arnos is quite pleasant. He is remote from his fabrication facility, which adds a little latency to delivery-related questions, but he is very responsive and helpful
• Delivery was delayed by a couple of months vis verbal commits when the order was placed. This seems to be an industry thing. Just need to factor this into your build plan.
• The headers and pipes (in brushed SS) are lovely. I opted for the Touring Pipes (which are quieter than the HP pipes). They are still "robust", or loud, but have a great tone.
• There are a few installation bits you should consider. These depend on your build. For example, the SBF is left shifted in the Gen 3 Coupe frame. Maybe this is transmission offset related, or the legacy of the Daytona - "Look out, there's another left turn coming up" or some other factor, but the right long-tube header for a SBF is about 3/4" short. This means one should avail themselves of the header flange 1/4" spacers available from Mark Reynolds / Breeze Automotive, to get the side pipes aligned. This comes with the need for slightly longer socket-head cap screws on the PS side. Just planning bits ...
• The ball clamp, which allows for side-pipe alignment cannot be tightened enough to prevent sag of the side pipes under use. The ball joint itself is intended to be a little leaky (per Georgie), but the clamp comes flush when tightening, which means all the torque in the world on the clamp bolt will not secure it adequately. As you may know, when the side pipe sags enough, and the pipes contact the fiberglass cutouts in the pontoons, the fiberglass will blister. The cutout done by FFR for the sidepipes is absolute $H!t in the first place (at least in my case), but this will need to be revisited if you are retrofitting the GasN pipes as I have done. Contact me via PM if you would like a hint at how to modify the profile of that sidepipe cutout AFTER installing the body :-)
• The fact that the clamp cannot fully secure the side-pipe is another hack to consider. Georgie suggests tack welding the side pipe to clamp to header junctions. This would secure things after the pipes are adjusted, but introduce the notion that those tack welds must be ground if the pipes are to be removed at any point for any reason. As an alternative, I am considering using some SS strip, maybe 0.080" thick to form and wrap around that ball clamp seam (under the clamp), to provide a bit more ball joint diameter to prevent the clamp from bottoming out.
• While the ball clamp design may be leaky (a bit), I believe it is sufficiently downstream of the wide band O2 sensor that is part of my EFI closed loop system. Note the ball joint of the FFR pipes is upstream of the O2 sensor, which caused me all sorts of problems with false lean detection on deceleration, and gagging on raw gas emitting from the side pipes 2' from my head ;-)

Net-net: I really like the pipes, and their sound, and doing business with Georgie. Just be aware that things are not always plug-n-play.

P.S.: Stainless Steel fasteners do indeed gall if they are not lubricated - Haha! Do NOT forget to lube the flange bolts if you use the SS fasteners supplied by GasN. I was hating myself for a few minutes this past weekend futzing with installing, deinstalling, grinding FG, installing, rinse, lather, repeat.

FWIW

I am hoping that I am done with my exhaust system experiments of this past two years :-)

Best ...

[Jphoenix]

Do the BOIG Coupe pipes come with the headers? For the price I expect they do - but can't tell from their website.

[LateApex]

I believe so. I believe you will need to decide and execute on your finish after you receive them. I may be off on this one ...

[LateApex]

I do not believe that Boig offers a twin side pipe design. The side pipes are a little larger overall, so have more of a snake-bite risk. They sound great tho :-) I think they are actually quieter

You will also need to weld a tab or some such for the pipe support if I am not mistaken.

[Jphoenix]

I do not believe that Boig offers a twin side pipe design. The side pipes are a little larger overall, so have more of a snake-bite risk. They sound great tho :-) I think they are actually quieter

You will also need to weld a tab or some such for the pipe support if I am not mistaken.

The Boig pipes appear to be the best option for me as the tracks I race at have sound limits, one track is 95 db.