hks hi power exhaust question

[eclipsegst3131]

i might be getting an hks hi power cat-back exhaust. i have found out it's 2.5". does anyone know if this exhaust system bottle necks to a smaller size to fit the stock cat? or does it stay 2.5" from the muffler to the cat? i'm getting a 2.5" cat-eliminating downpipe and i dont want my cat back to get smaller at the cat side. thanks for any help in advance.

 

[Eclipse99GST]

No it doesn't bottleneck. Full 2.5".

Erik