Yeah, performance wise other than the Joe Z pipe the mazzuri headers are the first thing I've seen for the IS350 that isn't completely crap from a cost-per-horsepower standpoint.
Some warning though-
Performance is still unknown right now- Daniel is predicting 30 horsepower, which'd be great if true, but nobody knows yet. With a little patience I'm sure he'll provide some 350 testing before too long.
Your check engine light'll be on all the time- this is a fairly significant problem, but hopefully they'll figure a solution.
You'll miserably fail any sort of emissions inspection since it deletes the primary cats- this may or may not matter to you depending where you live, although it's technically illegal in all 50 states. You may or may not be able to get an exhaust shop to under-the-table make you something to add in that'll pass emissions, but YMMV.