So I need a cat for my DA Integra with a B20 and was wondering what diameter would be best? I'm running a DC header with a 2" collector and a 2.5" catback exhaust. Should I just get a 2" cat, split the difference between the exhaust and header with a 2.25" cat, or go the same size as my exhaust piping with 2.5" cat??

I'm just not sure what is the best size to go with is when mating up 2 different exhaust sizes like this.

 

bump?

 

?

 

i'd go with the 2.5

 

i have a high flow cat if you would like to buy it.