I want to order a K&N for the UltraZ airbox.

1) Is it the exact same size as a WS6 airbox?

2) What size filter does it take?

I tried calling SLP, but they are closed for the weekend already.

Fred posted the answer on another forum. I'll put a copy of his reply here so it is archived and "Searchable"

I just bought an Ultra-Z, I didn't see any special whisper lid that's sold for it? Or am I not getting something?

There is no need for a different lid on a LT1 ramair car.

What year is your Ultra-Z?

99, and I don't have an LT1 at the moment.

Well, lol I guess it would be an LS1, but still.. I gotta no V8.

Correct, the 99 is a LS1, and yes that is a V8. You can buy a different lid for the LS1 airbox.

uh... yes I realise the LS1 is a V8, and that grass is green. I just missed something in the initial post. I somehow got the impression that people were buying a "specially desighned" whisper lid for the Ultra Z, instead of the standard one from SLP, or XYZ company.

Good thing, as my lid seems to work just fine. Thanks for the K&N part number though.