Roy,
I bought Lew The Taxmans TR-3550 when he swtched to a 3550-II, I didn't need the .63 OD, so the .83 is fine for me. (I can actually talk to a passenger when I'm on the freeway without yelling!!)
.I got a price from Hawk a few months ago(Kit is £645 + shipping etc.) which is around$1073 US + shipping) Let's stay in touch on this.
Take care,
Mike