anyone knows the tip size of the N1's... i heard that it comes in two version the turbo and NA(naturally Aspirated). The turbo has the tip size of 115mm = 4.5 inch (To big for me ).. and the NA version is about 90mm..But when i try to find it, they only have the 115 version... please let me know if that is true or is it only one n1 catback size 115mm ????