I thought I did alot of research on the secondary cat thing on the 4X4 Titans. I found posts on hollowing them out, or replacing them with straight pipe or resonators. Well now that mine are there but hollow, my truck is not starting up correctly. It takes a few extra cranks of the starter to get her going, and if I try using my remote start when the engine is cold it won't start. It will crank a few times and then nothing. Maybe I messed up. I thought the reading I had done showed that no codes or problems would arise as the secondary cats are downstream of the O2 sensors. I am thinking of giving my ECU a week or so to learn the new exhaust flow parameters before I go and order replacement secondary cats. This might be a expensive screwup on my part. Do any of you fellas have any advice?
Did you take the O2 sensors off to do this? If so, you might have damaged the sensors. They are easily damaged when removing / replacing them.
As for the gutted cats, most vehicles won't gain any power with gutted cats. I did a dyno test before and after gutting the primary cats on my Z and I lost 9 HP. It disrupts the flow of the exhaust since the exhaust is under pressure prior to entering the cat and expends in the hollow chamber and then has to squish back out of the exhaust pipe. It is better to have a straight pipe, but some state vehicle inspections will fail you if the cats are missing and have been replaced with a straight pipe. What you could do is either get a high flow cat, or build a cheater cat with your original cat housing (with a straight pipe inside the housing).
Check to see if you have any more o2 sensors behing the cat if so you just need to do a mechanical o2 fix its easy and cheap about 4 dollars @ pepboys or anywhere else if you have a drill and a drill bit,...