On my truck I've lowered my 1/4 by 1 full second at least! We dynoed on Saturday and I put down 281.1@5250 HP and 296.9@4500 TQ(on a Mustang Dynamometer). This is from a never opened up 2002 LS1 5.7L with 8Kmiles in a 1981 GMC truck. The mods are Airaid intake 2.5" true dual exhaust and Nelson tuning(yes it has the stock cats and manafolds). All I can say is get yours tuned by Nelson, you will love it!

 

well i dropped about 5-6/10 of a second with nelson. and some other mods.
but well worth the money
went from a 15.4 to a 14.6 hows that grab ya?