There are many different ways to do a "catch can" setup on a Miata, which leads to a lot of confusion on the topic. Hopefully this clears some things up and helps you figure out which route to take with your build.

Edit - Since I've received multiple inquiries about my flannel, here it is LOL https://amzn.to/3lcbCRy

Seriously the best looking and most comfortable flannel I own.
----------
Support TheCarPassionChannel on Patreon!
  / thecarpassionchannel  
Want to make a one-time donation? You can buy me a gallon of E85!
https://www.buymeacoffee.com/carpassion
Interested in having a 1 on 1 video call? Details below:
https://thecarpassionchannel.as.me/
What’s that digital gauge in the dash?! It’s called a CanChecked and you can pick one up from my friends at Bofi Racing!
https://bofiracing.co.uk/?ref=7465 (Car Passion affiliate link)
Check out my Amazon Store!
https://www.amazon.com/shop/thecarpas...
Use coupon code CARPASSION50 to save $50 on your first High Performance Academy course!
https://hpcdmy.co/cp10
---------
Parts Used/Mentioned:
3/8" NPT Tap Set https://amzn.to/3mpch16
1/2" NPT Tap Set https://amzn.to/2ZVDZuX
Evil Energy Catch Can https://amzn.to/3isZJEO
Mishimoto Air/Oil Separator https://amzn.to/3oucRgN
3/8" NPT - 10AN Fitting https://amzn.to/3vwQiJM
1/2" NPT - 10AN Fitting https://amzn.to/3iuW1KW
10AN Hose (5 feet) https://amzn.to/3F9cWwp
10AN 90 Degree Fitting https://amzn.to/3FkXnBN
10AN Straight Fitting https://amzn.to/3BgZ0Oy
Testors Red Model Paint https://amzn.to/2WB4pkg
VHT Wrinkle Black Paint https://amzn.to/3mm3Cwr
CitriStrip Paint Stripper https://amzn.to/3a2oYcr
SPS Motorsport Vented Valve Cover
https://sps-motorsportshop.com/shop/e...
Mazda 323 GTX PCV Valve
https://treasurecoastmiata.com/i-2379...
----------
Forum Links & Videos Mentioned:
How to Wrinkle Black/Letter Fill
   • How To Make Your Valve Cover EPIC! (R...  
MiataTurbo Catch Can Thread
https://www.miataturbo.net/engine-per...
fourwhls AN Fitting Upgrade Thread
https://www.miataturbo.net/engine-per...
----------
0:00 Intro
1:02 PCV Valves, Breathers, & Blowby Oh My
2:27 Why Upgrade?
3:45 Seeing The Parts On The Engine
6:05 Valve Cover Disassembly
6:50 Modification Variations & Explanation
9:18 Breather Passage Drilling & AN Fittings Install
13:13 Paint Stripping
14:51 Kraken Manifold & Can Location
15:35 Catch Can Comparison
16:35 Custom Built AN Lines
17:04 Painting Valve Cover & Lettering
18:28 Final AN Line Routing/Install