What mods? A lot and they all added a little weight. First- the motor tubes are supposed to be paper. I thought they were overly fragile so I replaced them with
fiberglass tube from Apogee. The motor retainers are built into the nozzle bells which thread off. I removed the part of the bells that retain the motors and then glued the bells in place. I used aluminum motor retainers from Apogee for 18mm tube. Just above the motor mount unit, in the bottom of the BT-80 I glued in a 1 1/2" section of coupler tube. This is to protect the thin walled BT-80 from ejection heat. Above this I added a centering ring for a single 18mm fiberglass tube to carry the ejection gases forward. Since you already have a kit, the instructions show that the Titan separates for deployment below the cage. This was changed. The fiberglass center tube runs through the tank bulkhead and into the bottom of the upper BT-80 with a centering ring for deployment. This eliminated the removable upper stage for display. The display nozzle was also eliminated. Also while assembling the lower part I added small wooden blocks to attach the rail guides . Also the cage was reinforced with small pieces of carbon fiber plate behind the wide closed areas. They are not visible unless you really look for them. I also used JB Weld epoxy for all plastic parts. I thought that I would have trouble applying the wraps, but did not. I good ounce to nose weight was added to the inside of the capsule and service area.
After all of this, I am not sure it will fly good with two C5-3 motors. I am not sure that I want to risk trying to start two composite motors. Maybe it will end up as a display model like many others.
That's about it
