I'm pretty indifferent about whether you can use that mod on multiple piece of a set of fashion clothing armor. It's not like that' 6/2 makes the armor rating amazing. Throw a single delta amyloid on the steampunk clothing set. That's 10/8 right there. Also, none of this bypasses the encumbrance rule, so you still need a high enough body to support high armor ratings.
Actually the cheese he's advocating for does exactly that, the Delta Amyloids give 9/3 armor boos of witch only the 3 points of impact count for encumbrance.
You'll have to explain why you think that.
Here's what Guns put up.
This assumes a Body of 5 with Strength 3.
Form-Fitting Body Armor, Full Suit
-Biomonitor
-Nonconductivity 6
Synergist High-collar Shirt
-Delta Amyloid
-YNT SoftWeave
Synergist Slacks/Skirt
-Delta Amyloid
-YNT SoftWeave
Synergist Longcoat
-Delta Amyloid
-YNT SoftWeave
-Concealable Holster
-Concealable Holster
Vitals Protector
Leg Casings
Forearm Guards
Shin Guards
Now, a 5 Body would give a max of 10/10 on the armor without penalties. That setup, if allowed to work the way he says it does, gives 6/2 on the FFBA, 4/1 on the Shirt, 4/2 on the Slacks, 7/3 on the long coat, and +3/+3 with the PPP. Total of 24/11 armor, which he says would count as 12/10 (3/1 FFBA, 1/1 Shirt, 1/2 Slacks, 4/3 Coat, 3/3 PPP) for encumbrance. So if you share what he's smoking, he takes a -1 Encumbrance penalty on something that would otherwise cost him a -7 penalty. If you can't see where the cheese in this is, or why it is worthy of the phonebook, then we're going to have to have a long hard talk about this thing I like to call "game balance". This kind of drek is no different from crap like Pun-pun, the War Hulking Hurler, and all the other insane crap that gets put up on the WOTC forums by optimizers. Any DM who allows this into their game should be forced to walk back and forth across a floor covered in legos barefoot until it stops being funny.