Dual exhaust questions

[LoweSpeed]

Hello everyone! 
 

I am posting for the first time here, so feel free to correct my post selection/delete it if needed. But, I finally picked up an R33 GT-R a few months ago and I am absolutely loving it! I got the itch to start installing some parts of my own on it (it by all means was not stock when I got it though). I’m mainly talking about the exhaust here and I haven’t been able to find any information on this subject.

The car came with a true dual exhaust and I haven’t been able to find a brand name on it, I doubt it’s a Kakimoto which seemed to be the major dual exhaust brand for it back in the day. And my questions are: 

1. What are the pros to a true dual exhaust on the twin turbos?

2. What are the cons to a true dual exhaust on  the twin turbos? 

3. Is there major boost creep issues on this the car if I get rid of the cats? (I don’t need them where I live)? 

4. should I go with a single exhaust from the front pipe all the way back? 
 

[GTSBoy]

1. There are no real performance benefits. It sounds different, and as the pipes are not as large diameter you can claw back some undercar clearance or run lower (if that's your thing).

2. Twin pipes, offering exactly the same cross sectional area as a single pipe** will have higher pressure drop - so will not flow as well. That's because there is more surface area of wall per cross sectional pipe area, hence more frictional losses.

** But of course, it is almost impossible to get 2 pipes that are exactly the same XS area as a given typical single pipe. eg, 2x2" is not the same as 1x 3", although it is close. If the 2x pipes add up to less XS area than the single - it will just be flat out worse. If the 2x pipes add up to a bit more than the single, then it might come out as a wash. If the 2x pipes are substantially more XS area than the single, then it will probably flow a little better.

3. No. Why would there be? What have cats got to do with boost creep?***

***But for f**ks' sake, please run a cat.

4. If you want.

[Dose Pipe Sutututu]

It will sound tragic and you wished you didn't have 1x exhaust per turbo.

There's a reason why most S55 owners change to a single mid pipe.

[LoweSpeed]

6 hours ago, Dose Pipe Sutututu said:

It will sound tragic and you wished you didn't have 1x exhaust per turbo.

There's a reason why most S55 owners change to a single mid pipe.

The car doesn’t sound bad at all right now, it just doesn’t sound a good as I’d like it. 

[GTSBoy]

Single 3.5", 5" metal body cat, centre offset oval muffler in the middle, large rear oval muffler straight through.

[joshuaho96]

On 1/10/2025 at 6:15 PM, LoweSpeed said:

Hello everyone! 
 

I am posting for the first time here, so feel free to correct my post selection/delete it if needed. But, I finally picked up an R33 GT-R a few months ago and I am absolutely loving it! I got the itch to start installing some parts of my own on it (it by all means was not stock when I got it though). I’m mainly talking about the exhaust here and I haven’t been able to find any information on this subject.

The car came with a true dual exhaust and I haven’t been able to find a brand name on it, I doubt it’s a Kakimoto which seemed to be the major dual exhaust brand for it back in the day. And my questions are: 

1. What are the pros to a true dual exhaust on the twin turbos?

2. What are the cons to a true dual exhaust on  the twin turbos? 

3. Is there major boost creep issues on this the car if I get rid of the cats? (I don’t need them where I live)? 

4. should I go with a single exhaust from the front pipe all the way back? 
 

There aren't boost creep issues, it's not engineered around the restriction of the cats but if you haven't tuned the engine a full decat + exhaust can flow enough air to run off the end of the OEM load scales and you will get a pretty substantial reduction in ignition timing as a result. I recommend using DFCO, avoiding ignition cut limiters, and avoiding popcorn tunes along with running a cat unless you enjoy a perpetually soot-covered and potentially burnt bumper.

Edited 2 hours ago by joshuaho96