Initial M30B35 Exhaust Setup

[EatsHondas]

Just got the M30 minimally wired up and idling with no exhaust manifolds. I'll be looking to get the exhaust made in the next few days.

Stock e34 manifolds > stock downpipes > Y pipe > 2.5" single > universal 2.5" in/out resonator > Magnaflow 12158

It'll definitely be on the louder side, but how loud should I be expecting?

[Lurker27]

Not that bad, ran the above with 3" and some chintzy ebay universal muffler. It will annoy others but in cabin it's fine.

Also just a b35 with a 4.10 diff was plenty of fun for hooning. I miss those days and want a second NA m30e30

[CorvallisBMW]

You'll be happy with the 2.5" Magnaflow, it won't be too loud.

[EatsHondas]

Cool. I don't want obnoxious, but I do want potent. We'll see how it goes.

[ahlem]

Try to design in a straight section or two in the event you need to add more muffler later. We used a similar set up on an M42 and it was loud enough to attract the attention of the State Patrol. I used two glass packs as resonators before a magnaflow clone on my m30 and am happy with the results. After adding a glass pack in addition to the Magnaflow on the M42, its got a good sound. The straight section was just long enough to add it in after donut man stopped me on the freeway for being too loud and missed the SUV that just blew by at 85.

[EatsHondas]

So the additional resonator helped further quiet the sound?

[CorvallisBMW]

Are you running a cat? Those help quiet things down for sure.

[EatsHondas]

Are you running a cat? Those help quiet things down for sure.

I'd rather not, I'm going to start with no cat. Maybe a hi-flow or something if it's too loud.

[EatsHondas]

It's loud as living hell at full throttle. There's no rasp, but the interior noise does interfere with normal conversation. It's acceptably quiet under very light cruising conditions, but if I get into it at all, it roars and takes off. It is a straight-thru exhaust after all, so now I know first-hand how much sound volume difference a cat (or lack thereof) makes.

[lukeADE335i]

A 2.5 inch single is pretty droney on an M30B35. I've never been 100% happy with the drone of mine, and I run a hi-flow cat. I put dynamat in various places on my rear bulk head, spare wheel well etc. to tone it down which helped a bit, but ultimately I'd like to go over to a twin 2 inch system like the e34.