Not sure, are they the stock dual setup? If so, thats probably why. Just get a low cel count (100-200) and you will get some good flow.

 

Yea, I dont like how the stock downpipe splits into two pipes at the bottom only to later turn back into one pipe after the catand then back into two again at the muffler. The downpipe the guy is making will only have one inlet and one outlet so a single inlet cat will work great. no need to split and rejoin and split and rejoin... etc etc

 

i think its kinda dumb also. All the awd cars have it also

 

yet another.... yay for FWDs!

 

im doing the reverse of what you are. im putting a cat back exhaust on my car 3" and then im gonna get a custom DP and High flow Cat both 3" since i foudn out throguh my last thread the 180Q does not have a manuf. DP.accordign to what i just read, i will lose low end power (considerable or not) if i have the stock DP and the Stock Cats with a 3" catback ? I have K03, which i would assume the same applies. Was wondering if there will be a problem with sencors if we only use one cat?


PS. I also dont like the plit on the DP and then into 2 cats and then back out into 1 pipe, but on mine its straight all the way through after the Cats.

 

catback wont cause any low end drop, a 3" dp will lose a tiny amount but more than make up for it with faster spool (see you dont really lose, since there is no lag already) and much more topend.

You wont have a problem if you use a cat with the o2 sensor. It will still read ~ the same amount of flow and not set off a cel