Buying First Twin Tip. Length?

I am 5'11" aswell and the shortest ski I would ride is a 178. I've been on 181 and 183s for the past 4 years (I've also been the same height throughout and weighed 140 lbs). The added length provides stability while riding and landing tricks, (take into account, now your bindings will be closer to center [if not totally center] so generally you will have a fair amount less surface area of ski in front of your boots making contact with snow, which at high speeds and awkward landings, makes washing-out more frequent.
Length= weight and stability.
If you are more than 140 lbs and just diving into the world of jibbing I would reccommend a 175-178cm 88-98 mm waist ski. But that's just my opinion.

yeah that's pretty short. if you havent skied much and dont plan to a ton and REALLY feel strongly about staying short, do it, doesnt matter

but if you plan to keep skiing a lot and getting better you should get something closer to your height. it might take a couple days to get used to but theyll def perform better in the future

I am your height and ski on 171/172s. Definitely on the shorter side of things but I would recommend something similar as it seems you are a somewhat new skier and having a ski that is closer to 180 might be a bit harder to get used to and won't add much benefit. That being said I wouldn't go below 170 ish.
Cheers and welcome to NS

VolkswagenHey guys

I'm buying my first pair of twin tips soon. I'm 5'11'', and last season I skied a short 160cm ski (non-twin tipped), and loved it. I tried a 170cm ski, but in comparison it felt clunky, and harder to spin.
I ski mostly park, and am planning on buying a 170cm twin tip. They reach my eyebrows when upright. Considering I enjoyed a 160 last season, would a 170 be the right length for me to buy? Is it uncommon for skiers my height to ride a length this short?
Any advice would be appreciated.

Really it depends on what you want to do. Also how stiff the flex is. I used to ride 195's and i am 5'8". Now I ride from 185 to 146 and I got to tell you the 146's are fun as all get out. They are fairly stiff.
Ride all lengths that you can. It will make you a better skier.
I'm on 146's right here.

I’m 5’9 and ski 171

In the end it's all your preference. I'm 6' and ride 185-188 mostly on twin tips. I also have a pair of frontside/carving skis that are 174 (probably could be bigger, but work just fine). Shorter skis are definitely gonna be lighter and easier to swing back and forth with a smaller turn radius, but won't be as stable at higher speeds or landing jumps.

Longer skis can be noticeable or even feel clunky at first if you drastically switch in sizes.

Depends on your skill too. Beginner, then it's definitely fine. Otherwise I vote 170-180, with an emphasis on being closer to 180. For you, probably 175. 170 just seems short imo.

I am pretty sure you already know this but the ski will be different when the bindings are center mounted. Riding a 176 with the bindings mounted back will feel way gnarly compared to a 176 center mounted. I'd go with the longer sticks because it won't take long to get used to and you'll feel a lot more stable and locked in when riding. At the end of the day, you know your skiing the best so choose according to how you feel.