200kss

Do you have that for GMC's?

Not trying to start a pissing war, but next time I see the truck I'll try to get a pic of the SPID sticker.

My factory exhaust is already 3.5 inch and the Magnalfow kit is $$$ so if anything I'll do the replacement Magnaflow muffler. Pulling an enclosed trailer with a CAI and different exhaust made me pack Tylenol on trips so I won't be adding much noise to this one.

My bad, I forgot that 2WD NHT's had 3.73's in '07. Actually it was a GMC CCSB 4WD. Bought it new off the lot, probably still have the window sticker somewhere. 6.0 Vmax with 3.73's. Sold it to a buddy of mine and loves it as much as I did.

No aftermarket grille. The truck is 100% stock down to the paper air filter, exhaust and factory chrome 20 inch wheels. Honestly fuel economy is unloaded is nearly identical to my 07 with the 4L70 and 3.73 gears. Tow/Haul was used 95% of the time. On previous trucks I haven't liked t/h in city driving, felt like a large stall convertor and wouldn't upshift (especially in an 01 2500HD we had). Experimented a bit and didn't see any change as far as temps go with t/h on or off. I realize LS engines make there power up in the rpm's but never have embraced the idea that 10 hours of 3000-4000 rpm pulling a load is ok. That's where I'll be running with the enclosed trailer hooked up. Trailer weighs 4400 empty and we put 4000 worth of stuff (car, canopy, cooler, etc.) in it. We only make 1 trip a year like that so a gas guzzling HD for the rest of the year didn't make much sense. Now looking at the basics of modding, the replacement Magnaflow muffler, CAI kit and possibly a tune.

Thanks for the reply. I did some research today and see that my temp. wasn't as big a cause for concern as I first thought. This truck is still being broken in, turned over 4000 miles on the trip. My previous Vmax had the 4L70 with 3.73's. I was on the fence between 2500HD 6.0 w/3.73's or a 1500 w/6.2. Bought a leftover '11 and thought it was strange this truck had 3.42's as apparently all the others I had found were NHT's with 3.73's. Lesson learned.

Just got back from a road trip while towing with my 2011 L9H 4WD non NHT. Had 4 people in the truck, pulling an alum. open car trailer and a 3500 lb. car. Love the 6 speed auto but would like 3.73's over the current 3.42's. Cruising at 75mph in 100 degree heat, the trans. stayed in 5th most of the time with downshifts into 4th on hills. MPG was 10-12 running between 89-91 octane, all had 10% ethonal. My only concern was the trans. temp. On the highway it would run 175-190 depending on hills, but in stop and go traffic it would go right up to 196 with a peak of 205. My 07 Vmax never got that hot even when pulling an enclosed trailer. Did NHT trucks get a bigger trans. cooler?

Save your money and just buy the muffler #12909. It will fit with a little modification. Thanks for the p/n. Any soundclips online with just the muffler (no headers)? Came up empty on a search. What kind of mods are needed with the muffler only swap? I'm sure my local exhaust shop can handle it, just like to give them a heads up.

Anyone going to try Maganflow's catback p/n 15121? I've run Magnaflow kits on my last 2 trucks but have to wait for a screaming deal to pull the trigger on this one. BTW, I switched from 87 octane to 93 octane and haven't felt any power increase, TBD on fuel economy.

Bought mine in Jan. and the only thing done to it so far is a window tint. It pulls better stock than my old 07 Vmax which had a CAI and catback, and this one is much quieter. Question: I have only run 87 to 89 octane so far, is there really a difference in hp and mpg worth running 92? Throttle response via drive by wire is still horribe too.

I'm reading through the thread for info. as I just picked up a leftover '11 Chevy that is nearly 2010LTZ4x4's twin. I was looking for a GMC max trailering 1500 to replace my 07 Vmax but ended up with a Z60 suspension 6.2 CC Chevy. I have an NHT/Max trailering question. What exactly comes with this package over the normal trailering package? I know gear ratio is one item as mine has 3.42's and NHT's have 3.73's. Also mine has 20 inch wheels which is a no-go on NHT's AFAIK. I keep reading about spring rates, anyone know the different rates or have any other info? I'll be pulling an open car trailer a lot and a 24ft. enclosed car trailer very seldom. If I pulled it more often I'd have a 2500HD but love the way the 1500's ride compared to the HD's when unloaded.