I just ordered my 6 gun/speed loader directly from banks. They still were having the Xmas sale. Shipped to my door $744. They said shipping date will be on the 10th., but we know how that has been. For heavy towing they suggest level 4. He said levels 2-4 are all fine, but 4 will give better mpg. I told him, I just want longevity in the truck with extra hill climbing power and he said it is perfectly safe for long term without any more mods. I already have the K&N filter with the Banks Monster Exhaust.
It took a while for my husband to let me get this, but I think he's convinced that it wont' hurt the truck and will only make it a better one.

My transfer flow tank/toolbox 50gal. combo, is waiting to be installed the same time.:o

How much HP is level 4?

Max power is suposed to be 135 hp, so level 4 should be 60% so around 80 hp? I was told level 1=stock, 2=20%, 3=40%, 4=60%, 5=80%, 6=100% of available power.

I think max torque was 305 ft. lbs.

You should be able to get equal or better pricing from stocking dealers like myself.
Plus we can give you a unbias opinion of the product which by the way is excellent.
I will be dyno testing this unit next week on my 05 LLY Crew cab dually, the dyno is tied up all this week with pescy race cars and will report the results and will have Superflow dyno sheets available.