Skip (WWE) is right....
The tune will support your speed , but nothing will support speed like pratice.
Box stock will perform for you, and a tuned whether it is a Ruger, Uberti or even a Genuine Colt will perform some better.
As to the .....
" some people dont like the shooters that use the short stroke kits " It not the Shooter that not cottened to,
it is the kit.
Each shooter/person has their own ideas & goals. Some find speed & winning at all cost the most important aspect and the most fun.
And believe the short stroke kit has a mili-second of advantage, added up over the course of the stages it does .
Others (and these are the shooters you'll find in NCOWS ) find that history, accratecy, and persona is the stronger draw.
There is no right or wrong , both style of shooter derives their pleasure from Western Action Shooting.
There is nothing wrong with a spring job and or bit of smoothing make a good box stock whatever even more a pleasure to cycle.
Just as a tune-up to the family sedan benefits the vacation drive .
"Does a beginner need to modify guns to be competitive to some extent or can you go out with stock guns and keep up with most?"
short answer ....
IS NO to the first question and yes to the second question Join the game at the beginning, and see where it takes you.
What part of the country are you in ?