Many? cars have what's known as a manifold Heat Control Valve, aka "heat riser".
It basical blocks off one side and forces hot exhaust gas across the
intake manifold below the carb to help promote fuel atomization when the
engine is cold. The exhaust then goes out the other exhaust pipe.
As it warms up, the valve opens. On a warm engine, you should have exhaust
coming out of both pipes. If you don't, the valve is probably stuck
closed.
Older cars used a thermostatic spring to control it, while newer ones
often used a vacuum diaphragm to activate it.

I thought a TF was a four cylinder?

In any case, a situation where only one exhaust pipe works is usually a
sign of a stuck heat riser valve.  Do you also have problems with vapor
lock?

nate