I highly recommend wrapping the drop-in with foil as well… Just wrap aluminum foil around the base of the drop-in to make a tight press-fit with the body of the host. Just make sure you don’t get too much foil where it can wrap under the pill and create a short…
This will help with transferring the heat to the body of the flashlight as this drop-in will get HOT quickly on high…
I just got recomend these by Boaz also which seem pretty nice. How do they compare to the drop in you guys recommend.
Those are good to start with. Still wrap them in foil like keltex78 showed above when you get them. I believe the 504b needed less wrapping of the drop in. I had the 504b from DinoDirect in silver and if I remember correctly it was decently driven @2.0A. Very good starting points 
I think DD has a coupon code out now that gives some $$ off. RETAILMENOT10OFF.
Not sure if it will work on those lights tho.
How do those compare with the XML drop ins? Is that a better buy?
Got 504b in yesturday with batteries from manfont all on the same day. seemed weird that it was the same day but worked out for me. awsome light but i think expected more. It seems like thin metal and my tail button was ripped. i also dont like how hard it is to push it on since it sits lower than the bottom of the light. still way brighter than my surefire 6px pro