Absolutely the plumbing, there’s ways to do it but honestly I think twins would be easier so you wouldn’t have the crossover. I’ll get some closer pictures of what I mean on how tight it is (especially on an early a) there’s about a half inch between the lower radiator hose and the same to the electric fan. We went to a 2” crossover and probably couldn’t fit much bigger, with my setup but it’s got a 26” radiator and electric fans so that may be taking up a little more room.