The BC stuff is good IME, had a Spec III on my car. Got fairly decent results with it, although I have a sneeking suspicion that I'd have seen a couple more ponies if I'd had a Spoon exhaust and more still with the Toda.
IMO, Spoon vs BC, I'd take the BC exhaust, it's lighter and doesn't have the price tag or dodgy aesthetics of the Spoon system. That said the 2nd hand price of Spoon systems has dropped loads as they've become about the most common exhaust on the CTR.
If you have the money though I can't recommend the Toda system enough, it's not loud in the slightest which makes it ideal to mate up to a race manifold. BC exhaust + race manifold = way too loud for road use, infact my Spec III was damn loud with a stock manifold. Spoon + manifold is loud, but not much louder than a BC exhaust + stock manifold IME.
So:
Not planning on manifold: BC for the cheap option, Spoon if not
Want Manifold: Spoon possibly, although Toda would be best bet