when all said and done
go to my dyno garage seatofthepants perfomance
are you a sponsor 
thats horrible…maybe ill get more with ported heads and a bigger cam??
http://www.fbodycentral.com/forum/showthread.php?s=&threadid=16083&highlight=lt4
there are some people deabating the lt4 package here
ok…i am going to get in contact with u soon…and see what to do excatly for my car…thank u
Here was a response from a knowledgeable person at an f-body site a while back when I inquired about the LT4 package:
The claims for LT4 conversion are based on a test by MORE Performance many years ago. They got 429HP on an engine dyno. They used LT headers, a larger throttle body, and a few things they apparently “forgot” to mention, including a $3,000 aftermarket ECU. But I think the results available from the people who ohave done the conversion indicate that WITH PROPER TUNING you can exceed 400 flywheel HP with the conversion.