Hey,
Had a few mates who have had them. One was a chinese (pretty much JJR) one on his silvia, leaked like crazy at idle, sounded alright ish. another had a custom one on WRX, had a similar style divided made on the downpipe, still leaked a bit, sounded better than the silvia. Another had a custom one on another WRX, pretty much the same only had the devider welded to the turbo itself. Sounded great, very similar to an external, nice and crisp when it opened. All of them illegal though, but hey, ya get that on the big jobs so upto you
this is what it will sound like: