Transmission Slippage From Straight Pipe Catalytic Converter from 1st to 2nd

[Ricker]

Maybe someone can help me explain this. I recently took the cats of my 2003 Yukon and replaced it the stock muffler with a single in duel out muffler. Pretty stock, nothing fancy, the cats were falling apart so i figured just straight pipe them. The back to Cats are simulated and the transmission was running just fine and shifting fine days ago before this previous operation. Today however, the truck while shifting from 1st to 2nd shifted perfectly fine but it feels as if the exhaust cant escape fast enough and sorta "chugs" after the shift.

Im wondering if this is due to to much flow from the cats being cut-off or if maybe i should start thinking about a Servo.

Any thoughts are welcome! It happens about 1-2 seconds after the shift. The muffler installed was just another brand new stock GM Truck muffler.

P.S. Any ideas on a new exhaust system that sounds low and mean but not raspy at all? I was thinking Magnaflow Cat-back with some new Cats installed but I'm unsure!

Thanks for the help in advance! You guys all rock!

 

[jdpber]

removing the cats changed your back pressure and the computer takes readings of this.. resultantly your computer is receiving odd pressure readings and changing the way it performs.. normally when people do cat delete/headers they get a tune to prevent this issue... check your state inspection rules before a total delete.. but if you dont have a rule about cats.. i vote dont run them.. and bolt up a cat back and get a tune and call it a day... with a tune you will perform alot better in addition to sounding better with a nice exhaust

 

[Ricker]

Detroit doesn't have inspection laws. Big surprise i know. Anyhow, so you think that with the cats deleted and putting a magnaflow or evan fischer cat back exhaust on the truck even with NO CATS, the back flow should improve? Then have BB tune it?

I appreciate the advice!

 

[jdpber]

Yes your O2 sensors at the cats are taking off readings...

Like when a person installs Headers with no cats.. they need a tune.. the tuner turns those O2 censers off so this doesnt happen along with a few other things..

get a tune and by gosh dont run cats if you dont have to.. they are an huge power suck....