I have a 99 Ram 1500 ext. cab, sb. I wanted to build a dual exhaust for it but i noticed that it dual into the cat and single out, but the theres an O2 in the center of the cat and one after. Does anybody have a remedie for this problem? I was planning on running dual 2.5 all the way out the back with V-forces, and a set of removable cats just for emission testing(one in each pipe). Any ideas on how i can make this work?
Thanks

You can use a simulator while you don't have the cats installed. The front sensor is really the only one you're worried about. The rear (downstream) O2 sensor is part of the OBDII system and pretty much only checks to make sure the cat is installed. If you are going to have it cut out of the exhaust system, you can just have a bung welded in the pipe for your upstream O2 sensor and connect one of these ( https://www.casperselectronics.com/Merchant2/merchant.mvc?Screen=CTGY&Category_Code=Ram SCROLL DOWN item 104042 for RAM) to your rear O2 connector. I use them and they work great. Simulates a signal that you have and extremely efficient catalytic converter installed to your PCM. Of course this is not emissions legal.

Hope that helps

On my truck i have duals all the way with two H's one before the cats and one after the cats, that is where my two sensors are.