Cool thanks again bud i seen your post on the other thread too, i was actuall eyeballing those headers and have them saved haha. i was gonna pick up something like that and have this fella i know here add in some high flow cats behind them and finish off the rest of the exhaust and probly the tune and intake for now.

Another question, as with my car when i put lt's on it i had to delete the rear o2's and just wondered if i could actually still use them with lt's, basically would i have to get or use extensions for those as well or will the fit the length?

Reason being as this is a family rig and not gonna be a hot rod but i want better pep and mpg and see no reason i cant lay my foot in it every now and then haha.

 

Another quick question, what is better to go with when buying high flow cats, ceramic core or metal or does it matter cause they do the same **** haha. biggest concern is which will last longer.

This is the best deal i am finding on a pair of high flows but these are for a mustang haha which definatly isnt 6.2 liters would that matter they are 3 inch look like?
http://www.summitracing.com/parts/SLE-M31040/

Here is the best deal i can find with them seperate lol i suck at searching the web. again 3 inch in/ot slip fit but they are ceramic core those good?
http://www.amazon.com/High-Flow-Cera...2994416&sr=1-3

Figured id use this with those cats and headers and the x flow muffler wouldnt be a bad setup if it was still too loud for a family vehicle add a couple of bullets behind the muffler but i dont think the one muffler will be too loud in the cab.
http://www.amazon.com/Flowmaster-159...999069&sr=1-59

 

The problem with High flow cats is they almost always throw the "Catalyst below thershold" code because they are out of the acceptable range that the Computer is trying to read the exhaust temp/AFR at. In my eyes Its more trouble than what it's worth to keep the cats, but some people don't like the smell. If you really want to keep the cats on it though, Im sure you could get away with installing the Rear O2's without extentions. Keep in mind though you have to purchase the O2's bungs and weld them in place and make sure they are positioned right.

 

I've heard good things about Pacesetters Metalcore Convertors (Pace Setter 80-0068 Pace Setter MetalCore Catalytic Converters)

I also like the Magnaflow Spun series convertors as well (Magnaflow 59959 Magnaflow ''Spun-Cat'' Universal Catalytic Converters)

I would imagine the Metalcore Convertors would last longer.

 

Pace Setter 80-0068 Pace Setter MetalCore Catalytic Converters GOOD GOD MAN lol 156.99 per your hurtin me haha, the others are cheaper but i dont want to have to replace them often. What do ya igure the mileage would be on the metal core and the spun-cats whats the life.

But i appreciate it man i would really like to keep the cats on it cause i dont want a yukon denali xl smellin like a ***** out camaro while driving or sittin and ideling nor do i want it sounding like one, just a nice quite rumble when ideling and accelerating but when smashed will let ya know there is more to it if that makes sense "sleeper" style. After reading it though i figure metal core will be better cause they wouldnt plug up like a ceramic if it started crumbeling.

Couldnt you just turn that code off in the system with a custom tune or readjust it or somethin, i thought i remembered someone sayin something about that a while back in the OBX knockoff thread. Said his o2's were actin funny so he adjusted some parameters and stopped throwin that code.

I was also contemplating tossin some 1.8's on it to give it a little more bump, i already have them sitting and not using them right now they are harland sharp 1.8 rollers that are semi shaft mounted(i say that cause the only ones i reer to as a true shaft mount are the ones that run on a single shaft all the was down not one per cylindar). I think that will give it a little extra as well maybe 15 or more with the with a tune not including everything else, i highly doubt ill need to upgrade the springs for that.

The way i figure it all in all i should be hopfully just under 470 to the wheels with the shift kit and trans tune to help hold it and an aux cooler to keep things chilly. I could be guestimating high though but i am talkin all mods the full exhaust with headers, rockers plus custom tune. All that should net me some good gains to my highway mileage driving like a grandpa and still give me the added pep for getting through and around traffic and add the fun factor.

Thoughts.

 

Id guess closer to 400 at the wheels. My truck pulled 350ish hp and 360ish tq *corrected* with CAI,Tune, Muffler but then again that was only in 3rd gear so it was 10% low. Smaller/lighter wheels will help mpgs alot!

 

You got to pay to play brotha, 150$ per is pretty cheap considering what a muffler shop would charge you and they wouldn't install half as nice convertors than those.

You Could get the codes deleted from your computer and all would be fine, wouldn't affect gas mileage in the least. I don't know about the adjustment portion of a tune to get the high flow cats to stop throwing a check engine light.

Keep in mind about those roller rockers it would put additional stress on your valvetrain (Mainly your springs) cause your increasing the lift of the cam with those.

Far as HP# go, I hate to be the bearer of bad news, but i'd would be shocked if it could break 400 at the wheels, your looking atleast a 20% Drivetrain loss from the engine to the rear tires. Your denali would have to be pushing damn near 600HP at the flywheel to get 470 to the ground.

I will say this though, that mother will haul *** after full bolt ons and a tune !!

 

Yeah i thought about it after i posted but didnt mess with it i figured the post was long enough haha, 470 was a high guestimation, the 6.2 in the 09 and up yukon denali were the ones rated at 403 from the factory the ones before that 07 and 08 were high 380 but thats crank hp im sure.

Either way it will still scoot and i have springs i can toss on anyway with the rockers, later i may port and polish the heads and upgrade the cam with a stock LSA unit but thats pushin it since by that time i may just have the thing ready to be swapped with the dmax/ally .

I should expect to see what Brutal threw down then if i get an 09+ cause the sierra denalis were rated at 403 from 07 so thats a good start.

If i go as far as to start messin with the cam and heads she is stayin gas and goin sleeper but as mentioned i may just do the dmax/ally swap and pull the 6.2 for a regular cab short bed AWD toy id sell the camaro for that haha.

Brutal i bet if you had lt's and true duals you would have been tappin the 420 maybe with upgraded rockers for sure with even a mild cam yeah your cookin with gas then lol.

 

I am hoping to get some for my birthday in the beginning of October.
i plan on running LT's 3"y merged into a 4" pipe then to a 4"splitflow muffler.

I'll prolly also add an underdrive pulley and a catch can at the sametime.

This weekend i'm selling my 22's and going to some stock 17's with smaller tires cuz those 22's with tires were almost 33" Plus im looking for a nice 2/4drop. and since i can't find 4.30 gears for the 14bolt im stuck with 4.11's or 4.56's not sure where to go with those. I'm always one to go overboard,

 

I'd stick with 4.11's chip since you DD that truck, especially after you put the 17's on, that truck is going to rip *** out of the whole if you can keep it from spinning.