Hi Boris, first up, welcome to the wonderful world of Spyders & SpyderLovers! :thumbup:
As for your Sway Bar, often the first give-away is the colour - if it's black, it's either Original Equipment or you are gonna need to get down closer to see if it's A/mkt!
Most of the earlier A/mkt sway bars were painted some other colour (yellow, orange, & red were popular) but more recently they've all been coloured black anyway, meaning you need to look for the sticker or stamping on the sway bar telling you who made it. If there isn't a clear A/mkt label/stamping, then it's most likely still the OE bar; altho another give-away is if the Links connecting the sway bar to the body are metal &/or coloured, then it's more likely to be an A/mkt bar (but still not certainly, you can buy the metal Heim Links separately too).
If there are little plated half-rings screwed together to form a 'spacer' or fixed ring around the bar alongside the brackets & bushes that hold the bar to the body, so that the rings sorta fix the position of the sway bar relative to the body so it can't move from side to side as it flexes, that too is a give-away.
Another possible give-away could be the diameter of the bar itself, but you'll need someone with the numbers handy to tell you what the dia of the skinny OE bar dia should be & what generally thicker A/mkt bars might be, altho again, that's not a certain sign - better quality metals can mean an A/mkt bar is stronger than the same dia lighter OE bar. But if there are a two or more holes in each of the ends of the bar so that you can move them in for a tighter/quicker response or out for more flex & a bit less stabilising response, then that's definitely gonna be an A/mkt bar!!
There's probably some other methods to tell them apart too, but those above are likely amongst the most common - apart from your comfort ryding it anyway! Cos if you feel the Spyder is leaning or lurching a lot thru the corners (& it's not just centrifugal force trying to toss you off) then maybe you could benefit from a stiffer sway bar!
Hope that little lot helps. Good Luck! :thumbup: