Im gonna get a carsound, just deciding between 2.5 and 2.25. IM gonna be getting the rmf header which I belive has a 2.5 in collector, and my exhaust is 60mm(2.36).

Should which size would be best?

 

2.5

 

thats what i was thinking...but i heard the cats are measured according to outer diamter...so the 2.5 will be actually bigger. Can anyone confirm this?

 

Cats are measure by the ID. They are made that way so that exhaust shops can easily slide tubing into the cat from either direction and just weld it up. Your header is most likely 2-1/2" OD. You probably should start thinking about running a 2-1/2" exhaust also.

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by SMSP &raquo;</TD></TR><TR><TD CLASS="quote">Cats are measure by the ID. They are made that way so that exhaust shops can easily slide tubing into the cat from either direction and just weld it up. Your header is most likely 2-1/2" OD. You probably should start thinking about running a 2-1/2" exhaust also.</TD></TR></TABLE>

so in that case i should get the 2.25 cat?

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by strsi &raquo;</TD></TR><TR><TD CLASS="quote">2.5
</TD></TR></TABLE>
its not that hard, 2.5 is the answer

 

like they all said... 2.5"