Just joined the Avalanche owners group

Well I just came back from the dealer and traded my 2002 GMC Sierra Z71 W/5.3L for a 2003 Chevy Avalanche 2500 w/8.1L it has 66,000 miles on it. Only did it because I also just bought a camper which tips the scales at 9,000+ pounds fully loaded and while the Sierra would pull it I just didn't fee safe. I have the Superchips from the GMC I plan on installing and if I'm lucky the K&N FIPK from the GMC will also fit. Any recommendations on anything will be greatly appriciated.

You might check with the manufacture of the super chip and see if the one for the 5.3 will work on the 8.1 liter engine.
As for as the K&N filter if the 8.1 engine has the factory heavy duty filter already on it it may be as good or better than The K&N filter.
Check gas mileage and performance before changing the filter and then after.
And clean the K&N and go real easy on the oil on it. The K&N oil can get into the MAF and intake air sensors and throw them off.
And take good care of that trans get it serviced if it has not been done.
MT

I just notice your post is over a mo old.
Sorry about that if it is to late to help you just disregard the post.
MT