Here's a dyno graph I found over on the www.silveradoss.com forum. The guy replaced the stock tube with a K&N tube and gain 7 hp with the swap. He's a tuner for our trucks (www.pcmforless.com), sounds like he's got a nice SS.
Jim
http://mywebpages.comcast.net/bherter/04si...rintakevskn.jpg
Here's the entire post about dynoing his truck.
http://www.silveradoss.com/forums/in...showtopic=3711
00 silverado ext cab
5.3L Vortec, 3.73 gears with limited slip, Gibson shorty headers, Dynomax exhaust, Ported oem airbox, K&N filter, Volant intake tube, NGK tr55's, ASP pulleys, Yank 2400 TC, Predator, LT1 electric fans, Cadillac Escalade wheels and 275/60R17 tires.
Best 1/4 mile: 14.76 @ 92.23 with a 2.09 60"