like with anything more power comes at more cost, just trying to establish cost per pound.
And then obviously only having to bolt some bodies on and change a few sensors is easier then changing out an ECU and rad etc...
So obviously if you want the power then your better off with the bigger length etc
all about cost to bhp gain really :D
But again you need to think does this limit me in the future... or will you be able to get similar performance later with a shorter rad