If you want to pace yourself and get some of the basic stuff before a supercharger, here is a list that won't break the wallet..

As an FYI...I have an F150 so the HEMI engines maybe a little different, but probably not..

-- between $100 - $400
1) cold air intake
2) better/bigger throttle body <--recommend if you do some head work...match it up to a Port/Polish....very nice
2) headers
3) catback exhaust
4) better thermostat <-- not really performance, but helps out the engine...
5 a) Chip (Superchip, Diablo, etc.) <-- get this done pretty much last so that you can get it programmed to the "T"

or

5 b) Programmer (Hypertech, Diablo, etc)
6) Dual Electric fans <-- I would recommend this if you have a clutch fan, helps out a lot in the summer time and your engine is not driving that fan weight (trust me, those clutch fans weight a lot)
7) Under drive pulleys <-- some people argue about the help this has, but personal experience, it helps the engine work better and I notice the increase power off a dead stop. But, if your going supercharger, don't get this... your probably going to have to replace...depends

-- between $400 - $800
1) Head work (port / polish)
2) 3 angle valve job <-- five is nice, but not for the extra money
3) gears <--nice, but depends on what you want to do with your truck (i.e, street performance, hauling stuff in the bed, etc.)

Just keep in mind, the above is not going to give you the feel of a supercharger. And, if you do the above slowly, you may not even feel the change because it is going to be subtle... but if you dyno stock and dyno when you have everything, you will see the difference...

I don't know the policy with this site (about suggesting other sites), but if they don't like this, please delete the reference...

but if you go to www.troyerperformance.com you will see some of their performance packages. I would suggest looking there to get a good idea of how much HP you will get with various performance pieces. I have used them for a few years with my F150 and Mike Troyer, is by far the most knowledgable person for, at least, fords that I know.

Anyway, hope this helps..

EDIT: I just checked the site, and there is no Performance Packages outside of Fords...but take a look anyway. I am sure that their suggestions about the Ford engines apply to HEMIs. An engine is an engine (make them breath better, burn fuel efficiently, and your increasing HP & Torque)