I was talking to my service writer @ the dealer. They just installed about 10k of performace parts for someone. Vortec SC, Mugen Header, Mugen Ti exhaust. Then they dyno'ed the car. It was 274 RWHP. From what he was telling me they (tuner and the Tech) thought that the Mugen Ti exhaust was a limiting factor. He said that the laws in Japan on exhausts makes them some what restrictive, and that a straight-thru exaust design would have improved these numbers.

Any comments?

 

The Mugen exhaust is known to create little or no horsepower, but not necessarily to lose horsepower. If you want to go the performance route a titainium single exhaust is going to be the best of all worlds (looks, weight, performance)... except for maybe sound.

Chris

 

Despite manufacturer claims, I've never seen anything done to an S2000 after the cat have any effect on horsepower. Amuse N1, J's Racing, Tanabe, stock, simply cutting off the stock mufflers... I've been to dynos of them all and there was no clear instance of one having any sort of advantage. Except this one car with the Mugen mufflers. Of course, he also had a Mugen header, bored throttle body, FPR, etc., for a total of a 5hp advantage.

I seriously doubt that JDM exhausts are overly restrictive. After all, the JDM S2000 makes more horsepower than the US version...

 

Here is a write up by Mugen on its header and exhaust.





Concept of development for Mugen S2000 parts

April 2001


<Exhaust Manifold Kit>

1. During the development, the performance test on the exhaust manifold by so many different specifications had been conducted and as a result, we were able to obtain many data. Some of them are as follows.

A. 45mm diameter of the primary manifold is better than that of 48mm.

B. When compared between 4-1 and 4-2-1, 4-2-1 is better in overall. General notion that 4-1 is for the high speed and 4-2-1 is good for the middle speed range is not necessary applicable to F2OC.

C. Exhaust manifold of standard specification was an ideal specification as expected. It is also a collector configuration aimed at the peak power output.

D. Regrettably, however, since the emphasis is placed on the mass production, the standard parts have the different primary manifold lengths for each cylinder and therefore, the engine performance between 6000 and 9000rpm is not necessary the best.



2. Actual running test has confirmed the following.

A. Since there is a brake master cylinder placed near the exhaust manifold, it is indispensable to place a heat insulation material such as heat insulation plate between the cylinder and the manifold. We have actually confirmed that there was overheating phenomenon when the test was run without such a heat insulation.



3. From the result of the test conducted, we decided the specification for Mugen