I have a Allums opti modded CS3 which I really like. But I found the stock CS3 wasn't thin at all. It was just noisier and not as sparkling. Between the level, tone, attack, and sustain knobs, you should be able to dial out any thinness. Start with all the knobs at noon.
the visual sound is just a dyna comp clone isn't it?
there are 3 basic types of stompbox comps out there. Dyna Comp/ Ross (keeley, analogman etc...) - optical compressors and orange squeezer types (analogman juicer). There are a few more but 90% of them fall into one of these three categories.
why do you want compression? What type of music do you play?
would you use the comp to even out your levels or do you want it to increase sustain during solos?
Humbuckers send a very strong signal into a compressor, so the compressor will tend to "clamp down" especially on the attack in an effort to even out the signal. This makes the attack feel spongey, and less loud. To get around that, I typically run the compressors Volume control way up, and the Sustain control way back.
What I find works the best for me is to first set the Volume control on the compressor such that - when you attack the strings hard with your picking hand the volume coming out of the amp is the same with the compressor "on" as it is when the compressor is "off". This is VERY important, otherwise the compressor will clamp down your signal too much.
This will usually result with the Volume control on the compressor being set significantly above unity, and on my CS-3 I run the Volume control at 2:00 - 3:00 when I use my Les Paul with vintage output humbuckers.
Once that's set, I then dial up the Sustain knob just enough to add just a touch of sustain, fullness, and ring - but not so much as to squash the signal. It's a very subtle thing, and I NEVER set the Sustain control on my CS-3 anywhere above 10:00 when I'm using a guitar with humbuckers.
Tone control is usually at noon, and Attack control (does this control even work???) is dimed. I'm guessing the thin sound you are hearing is probably the compressor clamping down your signal due to the Sustain control being set too high and/or Volume control too low. Possibly a combination of both.
FWIW, I own the CS-3, Barber Tone Press, and the Keeley compressors and I don't find the Boss unit to thin out my sound at all, and certainly not more than any other compressor I've tried.
Being able to tweak the compression ratio AND threshold makes it incredibly easy to dial in the right amount of effect for your rig. Virtually every other stompbox compressor has a fixed ratio, which strikes me as odd since there's such a huge audible difference between, for example, 2:1 and 5:1.
It's a dBX circuit -- definitely not another DynaComp clone -- which has an attack/release that for me is perfectly tweaked for guitar.
Huge amount of make-up gain, so you can really squash the peaks and still not lose volume.
Relatively low noise -- you can even use it in an effects loop.
No compressor is 100% transparent (that's why studios have racks full of them), but IMO this as close as you'll get in a stompbox.
The Maxon form factor is right up there with Boss in terms of reliability -- and it's true bypass.