Sorry for my very late response but due some rebuilding work on my home a lot of time is consumed.
About the kits! Well, I'm not that far yet selling it as kits, only can arrange the components right now.
Also supercharge a 5.0 schould be better to pick the 5.7GXI but I recon its your stock engine? its possible to use a VORTECH centrifugal blower from of about 2500 ,00 but you need to alter the fuel system, pulley and belts but never made the combination of a 5.0L with a blower since fuel air ratio must and blower pressure is different.
but starting with a pair of HI-TEk header will already gain some power.
If you want to know something else just ask
