A few weeks ago I purchased the Bisimoto pulse chamber exhaust in "spec" (stanless steel) finish. Bisi is in California and I'm in Ohio so it took a couple weeks to arrive (thanks to Naomi at Bisimoto for keeping me apprised of order status along the way).
Once it arrived, it looked like a piece of artwork. I just let it sit on my desk and admired it for a few days.
Installation was relatively straightforward with the exception that the exhaust hit my valence ever so slightly near the rear edge of the cutout. I was initially aghast at even the thought of taking an angle grinder to my car, but after taking a look at what I was working with, that valence gets pretty beat up over the years and it didn't feel like too much of a sin to grind away 1/4" of material or so from the bottom.
NOTE ON INSTALLATION: I think the fitment issues some have experienced are not the product's fault at all, I think it fits a perfect car perfectly. But, remember, when we (hamfisted and inexperienced) DIY mechanics do engine drops, we, at least for a short period of time, sit (or drop) the engine down right on the exhaust system, which has got to tweak it a little. That, coupled with the fact that the stock tailpipe is *tiny* compared to this unit, doesn't leave very much room for tweaking. There is probably also at least a little bit of wiggle in the heat exchanger's mounting to the head and in the engine mounts themselves, where even a fraction of a degree can mean a couple MM at the tailpipe.
Once I fired it up, MAN was it LOUD A.F... Good sounds, not a bad thing to be heard, glorious actually, but it is LOUD. Fire-breathing dragon is the best way to describe it. From a pure sound-quality standpoint, I think its one of the best sounding exhausts I've ever heard. The burbles and pops on deceleration are just pure awesome.
My wife was sitting outside when I fired it up, and she immediately agreed that I should purchase the optional sound arrestor (I think she even offered to go to Bisi's site and order it for me). So, a few days later it arrived.
The arrestor seemed to do the trick and makes it much more socially acceptable. Its still very loud, but not so loud as to annoy other drivers. The arrestor takes some of the bass out of the sound and makes a little more raspy note, with a little less burble, but still enough. I've even driven it through a drive-through (although in general I don't like sitting and idling in an aircooled car).
Even with the windows down, you can still carry on a conversation or listen to the radio both with and without the sound arrestor. Its not really that loud INSIDE the car, its a very directional sound.
Disclaimer: I am a crappy videographer and my phone's camera (used for the interior videos) sucks. I got a better camera for the exterior videos.
Also note that my car has a gutted cat, so a car with a functioning cat may be a little bit quieter than mine.
Here are two startup videos, first without the arrestor and then with.
Without:
https://youtu.be/3GY_rGJUrww
With:
https://youtu.be/mdFUbl1BI04
Now, here are two driving videos (interior).
Without:
https://youtu.be/Uj0Wwf0sIOA
With:
https://youtu.be/Q4kq_PtRPgM
Finally two more (exterior) driving videos).
Without:
https://youtu.be/K4s0f2auOWI
With:
https://youtu.be/He32zqaAsWg
User HWG09 also recently posted this excellent review video (much better than mine) that shows the install (it seemed to fit perfectly on his really straight car):
https://youtu.be/NuzIn000xi8
Performance-wise, the pulse chamber appears to have done basically what Bisi is seeing on his dyno. These graphs were made with an android app that I wrote for myself a couple years ago (because the ones out there are too gimmicky or simply inaccurate).
Here is a HP/Torque curve with the stock muffler
With the pulse chamber (no arrestor).
With the pulse chamber (with arrestor).
As you can see, the pulse chamber results in a 12 HP and 16 (15 w/arrestor) increase on my car, pretty much as-advertised.
In my final assessment, I love it! Most days I have the sound arrestor in, but if I'm going for a spirited drive in the country its really easy to pull the sound arrestor out for the day. Even if I were building a car with an unlimited budget, I don't think I'd use a different exhaust, this one is low-hassle and great value for the money and SUPER light weight.