I usually play 109 sngs on party and 4 table. I've been playing with a 4k bankroll on the site and usually cashout when I'm a above 4k. I went on a 25 buyin downswing in the past two days (and probably not playing optimally, haven't gone over the hands yet). Is this normal? What is the biggest downswing someone here has gone on in sngs? How many buyins should u have if you 4 table?

1) Playing 4-tables at a time does not affect the amount of buy-ins you need
2) It's different for everybody, but i really don't advise cashing out any money you make above a certain point
3) I can't say for sure as i don't play SNGs that much, but i think 25 buy-ins is a lot but there have probably been a lot worse
4) 4k seems a bit small to be playing 109 SNGs, but again it all depends on whether or not you can afford to go broke, which assuming from the way you cash out that doesn't seem as much of a factor.

I think playing STTs on a 40 buy-in roll is ok as long as you implement a stop loss. For example, as soon as you have a 10 buy-in downswing you drop down a level until you work back to have 40 buy-ins at the higher level. Allowing yourself to blow through more than 50% of your roll before dropping down is obviously not wise.

22 was my worst loss string. I dropped down a level about half way through it.