Lots of good options out there right now.
If you haven't, checked out
https://pewscience.com/ and his podcast The Jay Situation to do more suppressor learning than your brain can handle. Besides putting out really good info, he's an Aggie, so extra bonus.
I haven't shot every can he has tested, but I have used enough of them that the sound suppression rating he's developed comes in handy a lot and lines up with my own personal experiences on which cans are "quieter" than others.
I'm going to link the rankings table of every suppressor he's put on his SP5 and SP5K (the one labeled PDW on the chart):
The Cat Mob is the king of the hill right now. Its a really, really good suppressor. If you want the best, just buy it and go on with life.
The RS9 is a weird can, it likes higher pressure and is actually quieter on the shorter MP5K than the full size gun, which is opposite of how basically every other can behaves on the MP5.
He has also tested a lot of guns using a H&K P30L handgun, and that chart is below:
I included it so you can see where your Omega9K stacks up on a handgun compared to other tested suppressors, and also so you can see how differently something like the RS9 that has been tested on all three behaves depending on the host gun even with the same ammo.
If thats all super confusing, listen to some of his podcasts, read his write ups...it seems overwhelming, but the more you read and listen the more sense it will make.
I also thought this was a fun tool yall might not be aware of: cancontrast.com will let you compare suppressor sizes, which can be super useful.
From top to bottom:
Your Omega 9k
Rugged Obsidian 9
Cat Mob
PTR Vent 2
Resilient RS9
CGS Mod9X
OCL Lithium
Dead Air Wolfman
I thought the size comparison might be helpful.
For me personally, my PTR Vent 2 has been phenomenal. I have it basically dedicated to my Faux SD, which is a Turk made AP5 with a 5" K barrel under the shroud that I have direct threaded my vent 2 on. I could put a 3 lug mount on there to shorten it up just a smidge. With 147gr, the sound of the action is more noticeable and annoying than the gunshot. Its insane.
The only other pistol cans I've really used much on my MP5s are a Rugged Obsidian 45 and a CGS Mod9SK.
The Obsidian is nice in long configuration, less nice in short. The Mod9SK beats no can and is super small which is nice sometimes, but by far the least effective at noise reduction of the three.
Like I said, in your shoes I would buy a Cat Mod or Vent 2. They're way better than everything else right now if sound reduction is your #1 priority. Both can be used with 3lug, direct mount, most stuff.
But, if you want the option for a smaller form factor, something like the modular CGS Mod9X looks interesting, since you can make it almost as small as your Omega9k, or as long as the other options. Likely wont be as quiet as the other two, but will still be good and gives you more flexibility.
Hope that helped, let me know if you have any questions or want to shoot anything of mine!
More MP5 porn just because:
I even tried the Mod9sk on the FauxSD. Does it look cool? Hell yeah. Is it quiet? No.
