I would say very minimal, as long as they draw air from the same place. By the way, why Weapon R? I heard people complaining about them. For me, I prefer K&N or Apexi.
do what conrad said before. Use civic intake piping and stick the stock airbox on the end. All around better for the engine with practically the same "gains" as a cone filter.
I made a homemade cold air intake using 3" PVC and a K&N cone filter positioned directly behind the lower front air dam. I felt a minor increase in performance, but I like the sound it makes. However, the increase in performance is so minimal that you will quickly get used to it and wont even notice it after a week or so. I'm sure my homemade intake moves as much or more air than the $120 brands, but the opening in the throttle body is still as small as it ever was.
CelicaHobby.com is an independent Toyota Celica enthusiast website. CelicaHobby.com is not sponsored by or affiliated with Toyota Motor Sales, USA, Inc. in any way. The Toyota and Celica names and logos are trademarks owned by Toyota Motor Sales, USA, Inc.