Hey,

Is significant amount of back pressure lost when replacing stock DC5 honda cat back from original 2" to 2 1/4" pipes, resi, and sports muffler? Is the Honda resi and 2" pipes the way to go for optimum back pressure with sports muffler perhaps? Is more back pressure better for an N/A car like the Honda RSX???

 

I think you should be fine, considering that a lots of the big number N/A K series guys use 3 inch exhausts.

 

needing a certain amount of back pressure is a myth. the best headers on the market are designed to scavenge as much back pressure away from the exhaust ports as possible.

think about it: if there is a significant amount of back pressure trying to force itself back up the header and into the stream of exhaust gasses being pushed out of the combustion chamber, the pistons pushing the spent exhaust gasses will have to push harder therefor reducing power overall.

look at all motor dragsters, they always use open headers and large dia exhaust systems. just my $.02

 

I don't know about what rsxpat said but your catback is barely bigger than stock and you aren't going to lose any significant ammount of backpressure.

I have a DCRH, 2.25" piping, a Magnaflow resonator and muffler and "felt" a gain after installing each.