well, i changed out the original bulb because it seemed to have a pretty blotchy beam.
i wouldnt mind testing the original halogen, but i broke it up to create a pr base for an led.
anyway, you can get the kpr 113 and kpkr 103 from radio shack, but i got mine from walmart. i think they were $150 for a 2 pack.
i find that the kpr113 is very nice--for me, the beam was MUCH improved over the stock bulb. it might not be as bright, but i cannot be sure. it is a bit yellow, but it should be reliable, because im not overdriving it. but the lithiums will probably drive it a bit harder ( i will probably test the lithiums tomorrow).
although i love bright, i prefer a balance of brightness, reliability and runtime.
today i picked up the xenon xpr 103 at sears. they were $3 for 2. these things are BRIGHT! from the back wall of my garage to the street is 117ft. i can light up the inside of the garage BRIGHTLY at this distance. i just ran the light for 15 mins, and it did get pretty warm--but nothing melted. i have concerns about bulb life, however. im sure runtime will be greatly reduced.
the kpr 103 lies right between the xpr and kpr113 in brightness. it gets hot as well. havent tested it much yet.
i would suggest you do some inexpensive experiments: purchase some bulbs and try 'em out! you will probably need some spares onhand anyway.
Bob