You have to get rid of the low pressure area in the cockpit. To make this problem worse you add a tall wind screen and a top. I have the 2015 with a top (UP) and a short wind screen, I cut 3 inches off of the stock blade wind screen so I could look over and not thru which helps with this problem. I really never had this problem, but with a couple of things that I did I do not have the low pressure area anymore either.
We might have you covered. 
is it the twist dynamic top "Gull Wing" top. If so, R-Shot Windscreen will assist in this area.
R-SHOT Mesh Windscreen Now Available
I had an F4 at one point when they first came out. It's a good windscreen but it does cause a big backdraft. As @FunCycle was explaining, you've got a very high pressure are in front of the windscreen (as well as what air slides around and above it). You have a relative low pressure area behind the windscreen. The high pressure will naturally work it's way toward the low pressure. On a lot of bubble canopy aircraft they put a vent at the lower rear on the canopy opposite the airflow. same principle and the amount of air that moves in from the rear is astounding. The rear windscreen as suggested by @lrobbi, will cut down on a good amount of back flow which may your best bet. Other options are to cut a vent into your F4 (like you see on Goldwings) or switch to something like a Madstad that has flow under the windscreen and breaks up the low pressure area.
Contact F4 about a modified Gold WIng windshield vent. That should allow enough airflow to pretty much eliminate the problem, I'd think.
Display MoreWe might have you covered.
R-SHOT Mesh Windscreen Now Available
I really like your suggestion and have already started in that direction of installing a windscreen that will be attached to the front side of the role hoops with an engraved image and lights. That idea is a year and a half old and got put on the back burner because of the purchase of a house
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I really like your suggestion and have already started in that direction of installing a windscreen that will be attached to the front side of the role hoops with an engraved image and lights. That idea is a year and a half old and got put on the back burner because of the purchase of a house
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I really like your suggestion and have already started in that direction of installing a windscreen that will be attached to the front side of the role hoops with an engraved image and lights. That idea is a year and a half old and got put on the back burner because of the purchase of a house
Sent from my iPhone using Polaris Slingshot Forum mobile app
Yes you should feel a difference as long as it’s not a hard windscreen surface. I believe you will like the results
It sounds like @silver fox is talking about the acrylic windscreen @lrobbi...
Those didn't do much fox, just ask @DKF Texas who made the switch to lrobbi's TRUE windscreen.
Just saying... Save your money! 
@silver fox if your design doesn’t workout the way you wish for it to. Let me know if your interested in a R-Shot Windscreen- I give a 45 day money back guarantee. That guarantees simply means if your not happy with the difference in back draft air coming through - I will refund you the purchase price. But I agree with @FunCycle you may or could try to cut down the front windshield to get better results.
It sounds like @silver fox is talking about the acrylic windscreen @lrobbi...
Those didn't do much fox, just ask @DKF Texas who made the switch to lrobbi's TRUE windscreen.
Just saying... Save your money!
I have to disagree. I have a lexan windscreen on the front of my roll hoops underneath a slingshade with a nascar tall wind screen and it does a great job! I will say though that the tolerances between it and the body are closer than any that I have seen for sale anywhere on here.
@silver fox if your design doesn’t workout the way you wish for it to. Let me know if your interested in a R-Shot Windscreen- I give a 45 day money back guarantee. That guarantees simply means if your not happy with the difference in back draft air coming through - I will refund you the purchase price. But I agree with @FunCycle you may or could try to cut down the front windshield to get better results.
I also did two other things to get rid of the low pressure area
I have to disagree. I have a lexan windscreen on the front of my roll hoops underneath a slingshade with a nascar tall wind screen and it does a great job! I will say though that the tolerances between it and the body are closer than any that I have seen for sale anywhere on here.
Well yeah, you've almost got an enclosed cabin there, don't ya? 
That "almost enclosed cabin" is what was causing the problem. The huge low pressure area coupled with the natural flow of air from the back wheel up over the rear of the sling and directly into the cabin. Had we not done the lexan plate on the front of the roll hoops something would have had to go! I was/am running a rear exit exhaust which didn't help. I have posted before the video of larry's SS going down the road at 65mph and the two flags mounted on the rear of his sling blowing toward the cockpit. He has a soft top and not nearly as tall of a windscreen as what I'm running. There are ways to combat the problem but @lrobbi 's wind restrictor is good and has gotten a lot of positive reviews and there is no better guarantee to be had.
I know this all too well. Battled the same problems and compounded my issue by putting the dual rear exhaust on. My fix was two things. A complete (tightly fitting) rear windscreen and large UA rear wing. Gone are my issues.
I have documented the rear windscreen I fabricated. The one sold with LED lighting has large gaps in the bottom and doesn’t remedy this problem.
I really wish I could get mine replicated with company that can cut them at a price which isn’t astronomical like most other mods out there.
I really like your suggestion and have already started in that direction of installing a windscreen that will be attached to the front side of the role hoops with an engraved image and lights.
I had my windscreen initially placed in front of the roll hoops. It got filthy and was a pain to clean. Moved it to the rear of the hoops and it is easier to clean.
Here is what I fabricated in the garage with a buddy helping. Custom Rear Windscreen for Madstad Stinger Top
I have to disagree. I have a lexan windscreen on the front of my roll hoops underneath a slingshade with a nascar tall wind screen and it does a great job! I will say though that the tolerances between it and the body are closer than any that I have seen for sale anywhere on here.
I Agree to disagree with @MiM 
Not to mention it quiets down the cab a TON. I can have conversations and my music is enjoyable.
