2.5 is too big for a "dc2" (assuming its a vtir with the usual mods....) full stop.


IF you have heavy work , or supercharged etc 2.5 is great. But the usual intake/header mods do not justify a larger than say 2.25inch system

Noted that the cat-back piping should match the outlet size of the cat itself - which should also match the collector size of the header too.

IMO if it must be a 2.5 inch , use a standard ITR muffler or similar to tighten the sound and aid throttle response both down low and mid range. Back pressure is real and is needed on smaller engines.