So for the past few months my truck has been getting crappy mileage. I've been through everything, O2s, cleaning sensors, and replacing gaskets. Ive got the P0171 and P0174 codes(Bank 1/2 lean). I was wondering if the cats could be the culprit. Is there a way to test them and would cutting out the 4 and replacing them with two Maggie High-Flows give me back my MPG without screwing up my emissions?

 

Not sure if the maggies will give you back your mpg but I've had a set on my truck for almost 2 yrs and I have no regrets. If you do the swap make sure you get the old cats back from the shop, take them to a scrap metal dealer and get some $$ for them. I can tell you that I haven't noticed any loss in MPG with the maggies installed.

 

Bump. Do I need the pre-cats AND the rear cats? Magnaflow's website has a listing for both

 

^ Universal cats will work on your truck. You will just have to have a shop weld them in for you. You can also email Magnaflow and ask them if they have a bolt on kit.

 

You don't need the pres and the cats. I just had a set on universals welded in 2+ yrs ago. I got mine from www.hottexhaust.com part # 94136 is what I wanted but they didn't have any in stock after I placed the order so they sent me # 94036 at no extra $$. In hindsight I wouldn't have ordered the ones with the O2 bung in them. Turns out they had to cut back part of the pass. side heat shield to connect the OEM O2 sensor wiring harness to the cat. Unless you by a harness extention I get one without the O2 bung.