I am looking at getting this... http://cgi.ebay.com/ebaymotors...&rd=1

and wanted to know how much its going to cost to get flanges put on so that i can use it on my civic si. whats the stock length of the cat on the 99Si?

Will the 2.5" cat work with my exhaust setup? DC Sports cat back, and DC 4-2-1 headers. Didnt know if a 1/4" would change the bolt pattern. I guess it depends on the collector right? thanks.

 

you need to ask your muffler shop but roughly you'd be looking at 50 dollars, and if you have a stock cat for a 99 SI get under the car and measure itand you should be running a 2 1/4 inich inlet cat if your running a 2/5 inich od collector

 

im sure the USDM Dc header is a 2.25" collector not 2.5" im thinking that the 2.25" catco should be the one to go for. right?

 

i think that would be your better bet