mmbongo - still waiting to see some pics, and maybe sound samples too, of your upgraded Brute. From what I've read on here you didn't use the guard I mailed you . . . also, do I remember reading somewhere that you went with a little different then stock pup placement? (IDK - maybe that was something else entirely)
a2z, I'll PM you some more details, but here's basically what I'm doing:
Originally I installed Bartolini 59JS pickups (with an EMG preamp) in my JJX Brute. While they sound great for single coils, I just really missed that fat grunt that you get from that MM humbucker. Plus the B string was...well....weak.
So, I decided to covert it over to an MJX since all it required was a pickguard and a pickup. Easier said than done! As you can see, I looked for a pickguard for about 6 months. While Kevin's custom guards are phenomenal, I just couldn't justify a $250 pickguard on a bass I paid $300 for

For whatever reason, Kevin could never get any plastic guards to sell.
Long story short, I ended up with 2 pickguards, one new and one used. Once Kevin got setup with a distributor, pickguards were available. So, now I have a J/MM setup in my Brute.
I opted for SGD pickups over Barts, because like I told David at SGD....."I want to tear peoples faces off!" He made me a Neo MM pickup for the bridge, and a Neo jazzbucker for the neck.
I love the SGD pickups Dave made for me. I didn't even want a neck pickup because I never use them, I hate the sound of them. I planned on just using the MM pickup in series 100% of the time. But I'm anal about things and I wanted a matching SGD neck pickup, so I ordered the Neo Jazzbucker.
These things kill. These are the first pickups where I get to be...what I consider...useable tones out of the neck pickup. I don't use it alone, but the Jazzbucker combined with the MM pickup switched to singe coil sounds exactly like my buddy's Stingray 5.
Using the MM pickup alone and in series is where I get my 'tear peoples faces off' sounds. It's just huge. Parallel mode is also useable, still fat, but just brighter and less output.
The SGD's really brought the B string to life as well. I expected a difference, but not this much.
I'll post some pictures and sound clips when this project is done. It's holding at about 90% now, I have a few more parts to get to finish it up.