Don't bother improving great credit
Dear Dr. Don,
Would my FICO score be higher if I increased the credit limit on my credit card(s)? I now have $12,000 on one card. I have no credit card debt because I pay in full each month. It's my guess that my FICO score is about 800 or more.
-- Corny Compilation
If your credit score is bouncing around 800, I want you to stop wasting energy on trying to improve your score.
Trying to get to an A++ from an A+ isn't worth anything other than bragging rights at the homeowners' association picnic. And if you were bragging to me, I'd excuse myself to go find the horseshoe game, where "close enough" still scores.
Bankrate has partnered with myFICO.com to provide a FICO Score Estimator that will give you a better guess as to your current credit score. You can also consider registering as part of the class action suit against TransUnion and receive six months to nine months of free credit monitoring from TransUnion.
Having your credit lines increased may raise your credit score because it increases the ratio of credit used to credit available. For someone like you who doesn't carry a balance and already has access to a fair amount of credit, the impact should be negligible.
There's always the risk of unintended consequences here. Too much credit outstanding makes it that much harder for the next creditor to say yes. If you're managing your credit history with an eye on your next loan application, you don't want to get carried away with taking on additional credit lines you don't need.