xwindows over ssh after sudo?

ok...I'm stumped on this one. I cannot figure out how to carry over my environment variables with a sudo command. I need to install an application under root and only have sudo access to get there. I can use ssh -Y <host> and launch an xwindows session successfully as myself but as soon as I sudo su -, i lose my environment (as would be expected) and then of course the display varibale is missing.

How can I successfully launch an xwindows app on a system as another user?

How about running just su, instead of su -?

I'm so used to importing the environment never thought about leaving the "-" off. That worked....Thanks for the response.

No problem. I find it funny since I always had the opposite problem... "...huh? why can't root find fdisk?" and had to painfully reteach myself to use su -