Theres not a great deal of science going on here. Select biggest free flowing cone you can fit in the spare space. Next select the biggest intake pipe diameter you can to pipe to the maff housing keeping oem maff csa to maintain calibrations, pipe to turbo whilst maintaining correct temp rating of silicone. Consider running cold air feed to intake and possible shielding.
R&D my arse, more money than sense, a BETTER kit can be made for less. Not knocking it but doesn't anyone get pleasure out of doing things for themselves. Of course these kits are going to look similar the same happened with the
MK1 leon kits because there is only one main route to take, ITG hasn't reinvented the wheel here.
All of the
MK2 leon intake kits look good and considering your getting a TIP in essence too puts it on par with say a Mk1 dynatwist and forge TIP say price wise, but have a go your selves.