I returned my spare Turn One pump to have a leak repaired. It arrived back today with a modified cap. Perhaps it'll help prevent the common mist leaks.

new cap

That's a newer design but not that new. I think the original application was a dodge truck, I kinda remember buying one from the help section for my TPI pump years ago. I can't remember if my turn one pump has that or not.

FYI, that disk is easy to take off and put on a different power steering dipstick cap.

I noticed the disc was easily moved. It appears the orange rubber spacers under the cap are overall thicker also, which makes the cap fit tighter, but I'm not sure how easily it would be to move the orange spacers to another cap. That triggers my OCD a bit because I like the look of the OEM PS caps with the orange letters.

Those caps are, or were, pretty easy to get from a junk yard. That's where I got one for our CP car. 1980's V8 Dodge pickup, IIRC. It DOES help!

Before we got that cap, we wrapped the top of the reservoir with a wrist sweatband. That, too, works, but the sweatband does eventually get saturated with fluid and needs to be replaced. After the installation of that cap, no more sweatband.

This is definitely on my list now - I've been rocking the sweatband on mine.

I believe this is the one, although the cap we found for our car didn't have the pretty yellow coloration:

Dorman PS Cap

I'm pretty sure that dorman was the one I bought. For some reason I didn't like the cap (maybe the level was different than factory) so I swiped the rubber disk and put it on my original cap.

I grabbed an old Dodge truck cap at the wreckers last week and swapped the rubber flange onto mine. I ran an auto-X yesterday and it did stop the misting but the PS fluid just sort of leaked out the base of the cap instead. It may be useful to stop the mist onto the engine bay but you'll still need the hair elastic/scrunchy thing to collect the fluid.

Does the Dodge cap have an extra thick washer (or perhaps multiple)?

So I spoke with Jr at T1 just now. He said since I didn't sent a cap in, this was just a spare cap they sent to prevent any remaining fluid after the dyno test from getting out of the reservoir. He stated that I should continue using the OEM design, because it is designed to release pressure from the reservoir around 13psi when it gets hot, and if it doesn't vent the reservoir could crack. Sorry for the false hope

That tells me swapping the disk is the right move then. The disk should keep a lot of the fluid away from the cap as it vents.

Maybe the disk hung too low on mine and was into the fluid - I couldn't get it that close to the underside of the cap because it wouldn't slide over the spring. The system definitely had pressure in it after each run since it would hiss when I cracked the cap open. I don't think it was 13 psi though. I grabbed a second cap from a '95 Firebird with a 3.4 L that also had the rubber disk. I haven't even checked to see if it fits the LT1 reservoir yet.