I wonder what is used as a standart for not tuned, std Zetec E , with Focus Mk1 manifold, so propably 110-130hp,
for exhaust building.
I was going to use 2" tubes and 2" in/out catalytic, 2" in /out silencer.
But started to doubt if not better to go with 2,25 " ?
What do You use for engines with this power ?

Usual diameter guildline is:
Standard tune:
1,500-2,000 - 2in
2,100-2,500 - 2 1/4in
Tuned cars
1,500-2,000 - 2 1/4in
2,100-2,500 - 2 1/4in