Asking for some opinions on this ifak versus other  horizontal pouches like the Blue Force Gear and the Ronin Tactics ifak. Is the STOMP too large to wear at the 6 oclock position while sitting in a truck. I am looking for a horizontal ifak that is not too large, I have also looked at the Coyote Burrito. Just  looking for ideas and opinions from actual owners and users of the mentioned ifaks.

From my experiences with middle-back pouches of anything, the moment you sit in a chair whether it be a truck or patio furniture, you're going to be annoyed. They're perfectly fine when you're not doing stuff that involves sitting. I've migrated to just leaving the back area empty, and using a fanny pack. I rotate the fanny pack to my back when walking or running. If I get into a vehicle or take a seat I rotate it to the front. The STOMP is well-made, holds a lot, but it like other mid-pack IFAKs it's a somewhat niche use tool of your kit.

Everyone loves pictures right?

I've got a STOMP gen 2, and a fanny pack setup, and a BFG Micro trauma kit now.
It doesn't matter which one is at the 6 o'clock position, it's uncomfortable to sit down. The fanny pack is nice because you can swing it around to the front and you're good to go, in fact, i usually just leave it there.  If i'm wearing a backpack and not taking it off then the 6 o'clock pouch isn't as noticeable.
I kind of prefer the ferro roll 1 for the feel of lumbar support, but for me it requires wearing a carrier

@sevin8nin  Who makes the fanny pack?  I like the idea of using one of those instead of a dedicated aid pouch that might get uncomfortable.

I've been wearing my CTS Stomp gen 1 at the 6 o'clock of my belt under my plate carrier for 2.5  years everyday before I switched to the Ferro Concepts Roll 1 just a couple of weeks ago.

It is honestly slim enough to not be a nuisance when in a vehicle for hours at a time. However, this also depends on if you're wearing armor or not, how thick your plates are, etc. The thinner your plates or no armor, the more uncomfortable it is. It acts like a lumbar support.

After much research and reading your reviews, I ordered a STOMP. I will report back after I have worn it for a while.

I will not wear an IFAK on the belt line at the 6 o'clock position if I plan on sitting.  It's not comfortable at all, if you had to sit for any period of time you're going to have back pain and if you did that often enough who knows what you would end up with physically.  I also don't like wearing an IFAK on sides since that can make moving through tight spaces a PITA.  There really are IMO two good options: an IFAK you wear as a dangler from the front of your plate carrier OR the Ferro Concepts Roll 1 that will hang from the rear of the plate carrier in the lumbar area.  The Ferro Concepts Roll 1 will actually give you some lumbar support in conjunction with the plate carrier (plate carrier is already pushing your back out from a seat back).  Of course, there are no free lunches.  If you go the route of a dangler IFAK you've got this potentially big IFAK flopping around in front of you. If you go with the Ferro Roll 1 it is limited in what it can hold and you'll have to locate trauma shears and a TQ somewhere else on your person.  

@bdover the top picture is the Spiritus Fanny Sack but the bottom picture is a Longtucky Supply fanny pack instead. Pretty similar but a much better TQ holder on the bottom.