Hi, I've been lurking for a while and thought I'd offer a (hopefully) useful post. There's a motor factors called DRB in Warrington which is where I got my K&N filter from. Not got a Lexus (yet) - just an MR2.
Found their address on here if you're interested.
D.R.B Car Spares
25 Orford Green
Warrington
Cheshire
WA2 8PE
Tel: 01925 415294
Cheers,
Rich