I guess I need a little more help. An international customer pointed out that first class wasn't showing as an option on one of my kits. I changed the code as per RixStix's post in the previous page. That fixed it to a point. If I add 2 kits to the shopping cart it doesn't show first class international. I did some trouble shooting and I believe it's volume related.

My kits use this weight: 1.900000084 (1.9 lbs 84 in^3)

My Package Dimension Config is:
3x4x6;1.0
12x9x3;20.0
12x12x15;+

When I add one kit, the debug output is (first class is shown as a shipping option):
weight: 1.0lb, dimensions: 3x4x6
weight: 10.0lb, dimensions: 12x9x3
weight: +lb, dimensions: 12x12x15
Setting dimensions: l=12 w=9 h=3 for Weight: 2.25
Volume Filtering Enabled. Volume=84" cu
Removed 'Priority Mail International Small Flat Rate Box**'

But, when I add 2 kits the debug outputs (first class is not shown as a shipping option):
weight: 1.0lb, dimensions: 3x4x6
weight: 10.0lb, dimensions: 12x9x3
weight: +lb, dimensions: 12x12x15
Setting dimensions: l=12 w=9 h=3 for Weight: 4.15
Volume Filtering Enabled. Volume=168" cu
Removed 'Priority Mail International Small Flat Rate Box**'

For trouble shooting, I added a lot of small products to the shopping cart to get the volume up over ~160 in^3 and the first class option disappears.

Here is the mod to the code in the modules -> shipping - > UPSP.php

'First-Class Package International Service**'=>
array('maxWeight'=>70, 'maxGL'=>'', 'volume'=>200, 'maxLength'=>'', 'maxWidth'=>'','maxHeight'=>'', 'name'=>'First Class Mail Int Package'), // ID="15" **************I changed 12.5 to 200 to work with the kits. Kits are 84 in^3. But, if someone buys additional items the volume went over 85 in^2 SPIFF 020913**********************

What am I missing?