Not really. The only ones that acually will give you more power are open plentium ones like this:
http://www.turbocity.com/product_info.php?cPath=16_31&products_id=153 They build more power because they draw air from both sides of the throttle body.
The other 2 hole ones that are hyped all the time just move the torque curve down in the RPM range and make you feel like you have more power because throttle responce is better off idle.
They are thicker TB spacers and require adjusting and modification to the TV cable andlinkage to the transmission. If you dont get it right you can toast your tranny.
If you want some other TB mods that work check out this site also:
http://marine-performance-parts.com/gmthrottlebodyinjection/gmtbiperformance.aspx
The injector spacer and power charger will give you the most bang for your buck.