The Traxxas 2.5 pull start it will just screw right in to the back of the sirio iam using the 2.5 pull start on my sirio. You might want to use the E/Z start for break in tho (lots of compression).
The 2.5's EZ-Starter will probably be as much of a pain in the ass as the pull start.
The EZ-start 2 "stick" has a mechanism that will attempt to detect if you've hydrolocked the engine, and not push the starter if you hit it a few times without turning it over.
I put a Sirio in my gen-1 TMaxx... fortunately, I had the version 1 ezstarter that would power the starter as long as there was enough juice in the battery to use.
i love the pull starts. but then again i can always start my truck in less than 5 pulls. anywayz when u are doing break in, take and losin the glow plug a little so u dont have as much compression and then when it is going tighten it back up. it helps ALOT when u have a pull start and the engine has alot of compression.
but personally my self i hate pull starts, either the battery is dead or the cheap little motors went out on me. so i got used to having a pull start and it doesn't bother me any more. someday i might try the rotostart.
well i hate when i am really hyped up to drive my maxx and then all of a sudden my battery's don't have enough juice in them, and then i can't drive it for a while....
so i do want to get it but there are a million accessories that say t-maxx pull start, so i want to know which ones to get