05 denali catalytic converter question

[animalfries]

both cats are now in place and bolted up. turns out i needed a new o2 sensor in the rear probably fouled by the bad cat. i will get a sound clip up later. as for my personal observations at this point....the cold start sounds way more aggressive. however driving the vehicle it almost sounds.....quieter under acceleration. there is a charge of sound right before each gear shift in the 2000-2500 rpm range but nothing outstanding. like i said the vehicle actually sounds quieter while accelerating. i have a CAI under the hood also. kind of kicking myself for not having a cat back lined up because i needed to drop the muffler assembly anyway.
compared to the fouled cat, the new system has improved throttle response and smootheness. havent driven enough to note a difference in MPG although my yukon seems to accelerate more effortlessly than before proabably again due to driving with a fouled system.

vid clip of the start coming soon.

Any updates?

 

[showtime1k]

getting a p0141 code since replacing cat with aftermarket, anyone else get this

 

[BeaverGod]

way too much time has passed since doing this upgrade and posting a reply so i apologize everyone.
i have a video clip that was taken from my iphone but i dont think it would do any justice. if you want an impression of the difference in sound listen to a 2007-current stock escalade fire up with the 6.2.
i owned one of these for a little over a year before i got fed up with literally not being able to fit in the drivers seat between the door and that stupid center console that all the new GM's have (6'8" 270 here).
anyways with the magnaflow cats on my 05 denali 6.0 the cold start sound IDENTICAL to a 6.2 cold start which if youve never heard one, is one of the most beautiful sounds a stock motor and exhaust system could ever produce.
when driving there is almost no noticeable difference in sound EXCEPT for the 2200-2500 rpm range. there is a sound here that is slightly more aggressive than stock but still doesnt sound like an aftermarket exhaust note.

as for mileage im not noticing anything in excess of the stock mileage. 13-13.6 mpg around the city and 17-18 on the highway at 70-75. at 80 im in the high to mid 16's.

again i have the spectre CAI as well.

sorry again for the huge delay. if nothing else i know exactly the effect now as opposed to posting too soon after the replacement.

to summarize
stock cats 13 mpg city 17-18 hwy
bad stock cats with check engine light on a rattle in pass side cat 11 mpg city 15-16 hwy
magnaflow cats 13.5 city 17-18 hwy (able to get 1 mpg better at 80 mph than stock tho: 16.5 at 80 mph with magnaflow vs 15.5 at 80 with stock clean cats)