Custom 2.5” single for NA?
 

Has anyone made a custom 2.5” single for their NA 2nd gen? I currently have the racing beat dual matched with a single high fow cat but would like to lose some weight with the catback since its over 50lbs.

Are there any out there?

Did you guys gain or lose hp?

what are your experiences?

I’m thinking of making a custom single with a resonator and muffler and possibly a helmholtz in order to tame the noise a bit.

Interested in anyone’s experience doing something similar.

Thanks!

i'm not sure ive seen a 2.5, but basically anyone who built a race car was running a custom 3"...
hardest part is picking the muffler(s) you want to run. imo you do want something in the middle of the car.
in general the bigger the muffler the quieter it will be, also you want to use all of the factory hangers
actually i think an Apexi N1 single is a 2.5" single, its $$$ though.

pics for examples, N1 Single,
https://cimg3.ibsrv.net/gimg/www.rx7...ee30a16025.jpg

ERC, its actually turbo back, so the thing on the left is the downpipe
https://cimg9.ibsrv.net/gimg/www.rx7...0c8fb55dd9.jpg
https://cimg0.ibsrv.net/gimg/www.rx7...72dd3e8a4c.jpg
KSP, this might be down pipe back, but still two relatively big mufflers
https://cimg6.ibsrv.net/gimg/www.rx7...47d23efc68.jpg

FEED, this one has a Jasma certificate, so it should be pretty tame
https://cimg3.ibsrv.net/gimg/www.rx7...1eb75c3f9d.jpg
FEED Sonic R, i just picked one up, and i'm hoping the R didn't stand for Really loud, again turbo back, and you'd have a header there,
https://cimg0.ibsrv.net/gimg/www.rx7...b908a4e2eb.jpg

So one of the things that people neglect is length and construction of the exhaust tip on an NA exhaust. A lot of the drone and annoyance people are hearing are single thin wall - and short - exhaust tips on their custom setups. I recently built a simple and cheap Vibrant based setup using one of their 1118 mufflers and a 1141 resonator. Sounded like crackly ass until I massaged a 3" RacingBeat double walled tip. Same thing happens to the race cars I've built: cars sound annoyingly raspy even for a race setup using a Borla XR1, then I add a half step of diameter and 4-6 inches of tip and it clears right up.

edit: If someone is curious, the exhaust was mated to an RB road race header after a merge. At partial throttle it was actually pretty reasonable, get into it with the loud pedal and it could be annoying in a neighborhood but what I liked about it was that it was completely up to the driver.

Thanks for the suggestions. I had no idea Apexi had a 60mm version. However I think its going to be pretty loud based on what i've heard about it and that makes sense since the muffler is tiny. All of the others I don't think they are still being made new. So I'm still leaning towards making my own custom exhaust. I'm also thinking of going titanium for the crisp sound and lighter weight. Ticon makes a really nice larger resonator and thinking of using a vibrant tip. Should be crazy light but also super expensive.

Good food for thought. I never realized that. I don't want to have a screaming loud exhaust but wouldn't mind a little more noise as a natural consequence of going single so anything I can do to tame the single I will consider.

Here's a thought/ question. By the time you add enough mufflers and resonators to a single to get it quiet enough on a n/a do you really save enough weight to make it worth the money and time/effort?
I'm not trying to be a smartass. If you want a single by all means get a single. I'm just not sure if there is much weight savings if in the end if you end up with two mufflers and a resonator all in line vs. the RB catback.
I wouldn't think there would be much if any hp difference between a RB catback and a 2.5" single since both should have plenty of flow for a n/a.

Good point. So I'll add a little more context. I plan on doing this in titanium. Not because this is a racecar but because the I am trying to build a very clean NA FC. I have a pretty clean FD and want to pair that experience with a more daily-able rotary that has a sharp titanium exhaust note and because the car has so little power my main focus is weight savings.

Now, when I bought the car last year it weighed in at 2830lbs with a half a tank. By just removing the spare tire, tools, lighter suspension, removing the rear cover, high flow cat, lighter steering wheel, removing one of the rear tow hooks and replacing the steel hood with a aluminum one I have the weight down to about 2740. Now my next two large ticket items (other than stripping the car since I want it to be a nice weekend/canyon car with full interior) are the exhaust and battery (racing beat which weighs about 54lbs and battery which weighs in at 33lbs) I ordered an antigravity which weighs 6lbs losing a total of 27 lbs and my other big one is creating a single titanium exhaust which I project to weigh in at about 15lbs with two decent sized ticon mufflers (each weighs in at 4lbs-5lbs). I don't have the exact formula yet, but thinking this is what I'll need to keep the tone in check.

With all that being said I am willing to pay to create a titanium single with two mufflers weighing in at about 15 lbs total in order to have a crisper sound and lose about 40lbs of weight over the 54lb racing beat dual. For me its about the driving experience that I am trying to create in this car. With those two mods the weight will be about 2670-2680 and will feel much nicer to chuck into the corners and late brake.

With that being said, any input on single exhaust creation for the NA FC is appreciated!

so on the weight front, the single exhaust lets you remove the heat shields and hangers from one side. its a small weight savings, but it adds up.
there are also a bunch of little brackets (like the boost/pressure/map sensor bracket) which can be removed (its there because the AT cars add a thing to it).

Mazda started what they now call the Gram Strategy on the FC. the prototype was, too heavy, so they took everything they didn't already have on order and laid it out on the floor and had all the engineers go look for ways to save weight.
they still do this today, which is why the Mx5 is 2300lbs...

Edit: i'm trying to get mine to 2660lbs with a full tank and no driver. last time i had it on the scale it was 2620, but not a full tank, so i need to drop a couple Lbs somewhere. no AC/PS in mine, or bins or rear carpet

I guess I missed the titanium part somewhere. Those Ticon mufflers do look nice.

Well like I said, 1 muffler, 1 resonator, heavier wall stainless (that's still lighter than the duals you're speaking of) and an RB tip. It was certainly quiet enough for my tastes.

I didn't think of heat shields but yes, everything adds up. Thanks for sharing.

Getting to 2660 would be great! I don't think I'll get that low but close to it and still have a full interior, which is a goal of mine.

Do you happen to have any photos of your setup? Sounds like a good option if I don't splurge for the titanium.