New LS1 Owners - Newbie Tech - what's the difference between manifold sizes

i have 99 ss, and i'm looking into upgrading to a ls6 intake. i'm notice there's diffent size I.E. 92mm, 102mm, ect. i understand that the openings are bigger which allow more airflow, so my question is, why do people buy the smaller mm's

the ls6 intake opening is 78mm.the ls6 intake will work with power levels up to 450rwhp.the ls6 is very affordable compared to the fast intakes.the intake opening size is not the only thing that affects a engines performance,the intake runner length and shape.

so why don't people just get the bigger mm's. give or take there the same price.

Most of the smaller intakes have been discontinued now. 78mm, 90mm, 92mm FAST intakes are no longer available. Also, different TB's work on different intakes. That is a determining factory in how big people go as well. You have to remember that you aren't just buying the intake. The new FAST 102mm intake requires a new TB as well as fuel rails!

Jon

TSP has the best prices on fast 102mm intakes,and 4 bolt TB 92-102mm.the runners on the 102 fast intakes can be removed for easier porting or different runner sizes.