Kakimoto Exhaust - What Do I Have?

[Kip]

Been poking around on the new to me car. I've determined that I have a Kakimoto exhaust from at least the downpipe back (I haven't confirmed the downpipe yet). It has a catalytic converter. Other than the company branding on the exhaust tip, I can only find one other marking. Behind the cat and under the car is a plate that has the numbers "NF307FP" and "M11111". Unfortunately, the Kakimoto website is written in Japanese and my browser won't translate it. I found that Nengun sells the brand, but my exhaust doesn't look like their current offering. They do indicate that each pipe is custom made, but I assume that's more of an inventory control thing than some sort of special, vehicle specific tuning.

Anyone have a guess about what I have here? I'm getting ready to throw some dollars at tuning this car, but want to make good decisions. No reason to throw out a perfectly good exhaust system, if this thing will equal a full custom build.

Edited May 20, 2024 by Kip

[Duncan]

It really doesn't matter much who made it, unless if is obviously poorly routed or restrictive in a section; what matters is the nominal cross section. For most normal-medium power you go 3" from the cat back for a good combination of free flow and retaining ground clearance. Front and dump pipes are tricker to get in larger sizes and are the most common restriction

[Kip]

Thanks, Duncan. This is good info. The pipe is 3+" in diameter. I assume the cat is the biggest flow impediment right now. Then again, the fiberglass packing came shooting out of the car when I put it on the dyno, so I'm kind of de-catted at this point. I'm going to get under the car tomorrow to change the oil. I'm hoping I can scope out the downpipe and turbos.

[Duncan]

FWIW the packing will have come from a muffler, not the cat; they have a metallic honeycomb (if the innards are still there)

[GTSBoy]

1 hour ago, Duncan said:

metallic

More likely ceramic, but yes, possibly metal.

Another factor is that street legal (in Japan) aftermarket exhausts have to meet some noise rules that generally means that a 3" exhaust will likely have a 2 or 2.5" restriction somewhere inside it. If the exhaust has a JASMA tag on it, and hasn't had that restriction found and removed, then, the course of action is obvious.

[Kip]

3 hours ago, Duncan said:

FWIW the packing will have come from a muffler, not the cat; they have a metallic honeycomb (if the innards are still there)

True. That's a total duh moment from me there.

[Kip]

1 hour ago, GTSBoy said:

Another factor is that street legal (in Japan) aftermarket exhausts have to meet some noise rules that generally means that a 3" exhaust will likely have a 2 or 2.5" restriction somewhere inside it. If the exhaust has a JASMA tag on it, and hasn't had that restriction found and removed, then, the course of action is obvious.

This is a good tip. Two things:

• Will a JASMA tag literally have the word "JASMA" on it? If not, what does it look like and is there a common place to find it on the exhaust? Nevermind. I found some images.
• Similar question for the restrictor. Is there a common place it would be located or some sort of indicator that can be seen from the outside? Do I have to drop the exhaust and look around until I stumble on it?

Edited May 21, 2024 by Kip
New info found

[GTSBoy]

It's usually associated with a muffler. Often in the middle of the muffler, sometimes at an inlet. Not removable by just slipping something out. usually needs butchery (read outright replacement of the muffler).

There's absolutely nothing magic about any Jap exhaust brand. Totally generic. Totally replaceable with anything else that will do the job. I've replaced the centre muffler in mine a couple of times.