The exit of the exhaust on the 641 is in the diffuser. The kit only provided 2 rectangular photo-etched plates with an oval indent in the middle for people to paint it black to pretend to be the exhaust outlet. They are in the bottom of the car and no one can possible see them. But then, I still took the effort to open the hole up. Who would have thought that my former job of corotron and scorotron design and prototyping them came handy? I used to fabricate the screens by cutting small opening on stainless steel sheet metal. Corotrons and scorotrons are electrostatic chargers usually used in xerographic application before Canon came up with a better way of laying down a coat of electrostatic charge to a photoconductor using primary charge roller. Getting confused?
The picture shows 1 with 2 oval openings on the left and the stock one on the right. I'll work on the other one tomorrow.
Also put together the wheels.