Weights:
Stock seat with brackets: 42 lbs
Sparco w/bride brackets: 49.5 for a net gain of 15 lbs.
Keep in mind, the Sparco is a high end street seat with all the adjustments, not a race shell. Bride brackets alone are 9.5 lbs so they're no lightweights either..
I was surprised at how light the stock seats actually are. My old Audi seats weighed in at 52lbs +
Bracket adapted to the Sparco with no problems:
First seat in with no issues, passenger side tomorrow. On the airbag light, I jumpered the plug with a 4.7 Ohm resister. Made up a pigtail by cutting the connector off the stock seat instead of jamming the resistor into the car side plug. It can always be re-attached to the stock seat if I go back. Worked great...No light: