You need to regear.
1) You speedometer won't be off when you drive
2) You won't overheat, cook, and thus destroy your transmission.
3) It's more fun to drive since your truck is not a slug.
4) You stay in your motor's powerband, and will accelerate like normal.
5) Capability (if you ever choose to use it occasionally offroad)
6) Gears are THE best upgrade for the amount of money spent
I bought my gears (for 8.8" differential/ring gear) off of eBay for $48 (only had 200 miles on a mustang, and the guy decided to switch to 3.73 gears instead). Gear & bearing set was aother $30 for a full set with crushsleeves, etc. I installed it at a local mechanioc for $70. $150 installed, and I could not have been any more happier. Your tires will cost more...shit, one tire alone could be more!
On another note, I have a used Skyjacker Class II lift kit (with extended radius arms) that I never installed on my truck when I had it. Some bizotch T-boned me before I could do it, Interested?
Pete