Do a search under tri-flo. We have had discussions on this muffler a few times.
I can tell you I have one installed on my 540i and very happy with it... Sounds great and as for is it worth it??? It comes down to what you're looking for. Quality performance mufflers do cost money... Let's not forget, you're also paying for the name... Some of these products increase the horse power according to their reviews... Bavauto.com has some good info on tri-flo
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