It should completely fix it.

The header tanks have a weighted pickup in them - basically a length of fuel tube extending into the engine with a heave chunk of metal on the end.

This means that if your truck flips (and thus your fuel goes to the "top" of the tank), so does your pickup meaning that the engine still gets fuel...

It's a bit of a pain getting fuel into the header tank before your first run (unless there's still fuel there from the last run, obviously) but other than that it's just plusses

It should completely solve your leaning problem - it has for MANY other people.

HOWEVER, you will still have a problem of getting fuel into your header tank if you're running it WOT for extended periods. The simple fix for this is to bring it in for refueling before the main tank runs too low. If you empty your header tank, you have to load it up again (the pain in the arse mentioned above).

It's rare you'll ever come across this though. Especially with an MT, you tend to be stopping and starting quite regularly (when you're ligning up for a jump and what have you).

Hope this helps