To hell with K&N...get a dry flow or a Spectre filter...I run a Spectre...its cheap as sin and flows tons better than a K&N...buy it at Autozone. Your TB is 3.5"-ish and the filter comes with rubber inserts to help it fit better if need be.
Granted...that is a LS1 TB setup...and far from stock...but that is the filter I use.