What is a good charger for competitive racing? I just getting back into this and in the past have done nitro. I got a zappers 5800 for mod class.

I was looking at a Reedy 1216-C2. Any other recommendations?

iCharger X6
iCharger 406 Duo

When do you need a dual?

Icharger 406 duo is the go to charger for high level completion racing.

When racing, you do need 2 batteries at least

+1

More info here:
Which charger is the best?

Once you get more than one car, for example. Or to use the full 40A discharge/charge cycle for stock classes...

I wouldn't say that. You can manage with one per car (I usually do, without problems), but two can be more convenient.

You never know when you will need to charge your transmitter battery because you forgot the night before!
Also the icharger x8 and 308duo are good.

Not a necessity but having a charged backup battery can be a real saver. Other situations for a second battery would be, You won the B main and got bumped to the A main and some places don't allow high C charging.

I never charge my Tx at home, it has a USB port which is charged from the USB port on my charger at the track, typically gets topped off in about an hour and I will top it off between rounds throughout the day.

The track in our area will run the lower mains first, so if someone gets into a bump situation, then there's no problem getting their battery charged before the next main assuming they have a 40A charger, no need for a second pack. This is a justification for buying a higher quality charger and higher quality battery that can handle 40A charge rates so you don't need the added expense/hassle with maintaining more than 1 pack per class.

I also run 3 classes with a 2 port charger, typically have the first pack already finished charging by the time I finish racing my 3rd class and need to put that pack on the charger

What power supply do you recommend for a icharger x6?

Icharger is best all around.
i have beent told old hp server PSUs are the go to. I have mine on the way for my new 308

Any other options? I almost want an AC/DC power supply ready to go.

Anything that will comply to your needs? There is a uge topic about the X6, read it.

This is how I convert a power supply which I currently use with the iCharger 308

Thanks for the info. I decided to go the AC/DC combo route. I don't want to deal with multiple pieces. All-in-one is more convenient option for me at least.