Okay, I am installing a set of flowtech long tubes in my formula. All is going well with that but I was planning on keeping the factory cats and o2 sensors. Needless to say I didn't pay much attention parts on car until after I got them unbolted. Now old exhaust is all laying on floor of garage-which took a day to do- and the cats don't look like they will bolt up to the headers at all. Do I have to get aftermarket cats or any chance of making stock work. I thought about just cutting off old flanges and welding on new flanges. Any ideas would be great. Or is it just easier to buy new cats and y-pipe. Like I said, I am dumbass. I know, I will just run open headers all the time.

 

If you want to run stock cats, I think you will have to get a reducer. I think it will be easier in the longrun to get some magnaflow cats or something. Im guessing the collector is 3 in. I think the stock inlet on the cat is 2 5/8 or something. If you just get new ones, you can avoid the problems of your stockers clogging, and then having to change up your pipes again for another cat. (unless you get stock again, which im sure is expensive)

 

yea just get some 3" cats and bolt em right up tot he collectors.... thats my plan neways

 

10 seconds of looking at the stock exhaust should have told you that the stock cats wouldn't work.

besides them mounting totally different, and being of significant size, they are also much smaller diameter than most LT collectors.

buy new cats

 

I would be easier just to buy new cats and a y-pipe.

 

The headers are all on and sound great with no exhaust. I was a little disappointed in the bolts flowtech provided for the headers. To short to be any good. First one I tried to torgue to setting and the threads gave out in the head. It only had like 3 threads. Ended up using the stock bolts. I hope I dont' have any leaks. Would hate to tear it all apart again. Now to buy new cats and y-pipe.