i got the injen on my 3 and there was a noticeable gain in power, the only thing tho is that it comes all the way down by the front tire and every time i wash my car with an undercarriage spray it soaks my filter and it sucks in so much water that my engine will stall out, i dont know if thats the same model your looking at or if all cai's go down into that same spot, but make see if you can get short ram
if the filter is placed in the same location with the same size pipe, its not gonna be a real big difference between the two...