I managed to squeeze a Tillett B6 into my narrow body Birkin. It’s quite comfortable and lowers my position in the car which is good. Now I'm challenged by my belts (par for the course: one step forward, two back) previously I had the Birkin sport seats and looped the sub-belt around the front, there was plenty of room for lap belt hardware on either side. As you can see in this pic the B6 is a little wider and gives the driver lateral support. Consequently the hardware interferes with the belt holes through the seat making it difficult to fully tighten the lap belts. Now that the sub belt comes up from below it’s also a little....tight.
Does anyone have similar experience: I think switching to pull up belts may help. But I think ones with less space between the cam-lock and hardware is needed? Would switching to a 6-point setup help with the sub-belt position?