I wanted to spruce up the truck since I installed some 24's last fall and it killed the performance of the truck.....as much performance as a 6000 lb brick would have....lol. Anyway, truck is an 03 Yukon XL Denali, I had put a K&N intake, dynomax exhaust, shorty headers, removed cats and tuned last year and it ran really well and worked great. Threw the 24's on last fall and its slower than when I got it now.

I picked up some super low mileage 799 heads, already had some new Z06 valve springs, and ordered in a set of long tubes, as well as a comp XR265 low lift camshaft as recommended by comp. I figured this combination would bring the torque up substantially and give it a good bump in power as well. I haven't ordered the headgaskets yet, does anyone recommend a certain gasket thickness or application, we have shitty fuel here so only 91 is available.

As far as the parts I have now, is there something else I should change while everything is apart, truck has 100K on it, plugs and wires are new, as well as water pump, tensioner, belts, etc.

Any thoughts or recommendations?

 

Cometic .040 head gasket to bump compression a bit and throw in some new ls7 lifters

 

Going to lower gears would really help

 

A circle d 3200 would really help get that pig moving or you could just get rid of the wagon wheels

 

Picked up a couple more items, my tuner was concerned with street tuning only with the head/cam swap as the truck is AWD and his is only a 2wd dyno. Figured its hard to see where its at with the timing adjustments without a dyno so I sourced a manual shift transfer case with low mileage and swapped it out last weekend. I must say without all the extra gear and transfer noises its a much nicer drive and can actually spin those "wagon wheels"...lol. We also looked at the tune now and the truck is running close to 90% duty on the injectors so I picked up some new 8.1 injectors from GM and ordered all the rest of the gaskets. I decided to go with the stock thickness headgaskets instead of the cometic thinner ones, our fuel is pretty shitty here and it will be close to 10.5:1 anyway. Hopefully take some time off in the next couple of weeks and get everything done and tuned.

 

I think you made the right call on the head gasket. but not just for the shitty fuel. I like factory gaskets better than aftermarket...

 

Went to the dyno with a buddy today to get his car tuned and since I'm doing the work to the truck this week decided to run it on the dyno for a baseline to see where I am at now. Was really hot but put down 272 and 312 tq with the light mods I have done now. Hopefully can make close to 350whp next weekend after the parts are on.