ASM Siren Circuit Exhaust Review

After going through multiple exhausts, it was time to look for another one. The following have been on my car at one point or another in the past:

– OEM
– Amuse Dual
– Mugen Sport
– T1R 63mm
– T1R 60Titanium prototype
– J’s Racing 60RS
– T1R 70R-EM Titanium
– ASM S-Special 70mm

I soon decided to research the ASM Siren Circuit exhaust but had a hard time finding useful information for it. Pictures of the exhaust are almost non-existent other than the ones on display at ASM or their customers cars, all of which were shot at the same angle.

All that I knew about this exhaust before I ordered it was that:
1. it’s a little pricey
2. it looks weird
3. it’s designed to meet the Japanese noise regulations.

I’d like to thank Ben from A&J for the exhaust and Aaron from GoTuning for the information he readily provided me with. I have also driven S2000’s with quality exhausts so my opinion is not based on online discussions or youtube videos.

Six years ago, I started out with the intent to make my car sound just a tad sportier. But as I quickly got hooked on trackdays, my attention moved towards performance and weight savings. Over the past couple of years, however, my focus has slowly drifted back to my career and unfortunately the car rarely gets driven these days. This has brought me back on the market for a street-friendly exhaust that still makes proper sports car noises.

I was very satisfied with the S-Special actually with its sound and power. The exhaust was throaty at idle, had negligible drone under load, and screamed in VTEC. You could say I was curious to find out why all these people on ASM’s blog ditched their S-Specials for the pricier stainless-steel-exhaust Siren Circuit.

When the Siren was delivered, it had a small dent in one of the resonators. This really stood out like a sore-thumb from the otherwise very well made exhaust. I noticed though, that the exhaust isn’t exactly lightweight, and yet ASM went without the middle hanger. This is likely due to the size of the resonator. During installation, I also found the differential hanger bushing to be slightly pulled towards the front by the exhaust, which isn’t a big deal but unexpected for an exhaust with ASM’s name and pricetag attached. I later confirmed that to be normal with the other cars on ASM’s blog.

Anyway, onto the impression. One word sums up this exhaust really well: QUIET. The car no longer roars to life, and it does not have the aggressive tone of your typical aftermarket exhaust at lower RPMs. The car starts and idles very quietly. During normal driving I can barely notice myself running an aftermarket exhaust. From the outside, however, there is an unique hollow yet refined exhaust note that is unlike any other exhaust I’ve heard on the S2000, and fortunately the Siren still makes the right noises (albeit at a lower decibel) in VTEC, which is similar to the sound characteristic of the S-Special. One notable downside that was immediately felt was the power and response compared to the 70mm, but that really doesn’t bother me at this point.

ASM Siren Circuit in a nut-shell:
– odd-looking
– not the lightest
– not the most powerful
– sounds cool

Hopefully this review is helpful to those of you on the fence about the Siren Circuit Exhaust.

Based on an original write up by JL9000

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