I wouldn't pay too much attention to the answers above, here's my thought process.
The third gen Rx7's are for the most part turbocharged, and turbocharged rx7's will create a lot of backfire heat when thrown into neutral. The waste gate maybe hasn't activated and released any heat.
Since engine rev is high- the motor no longer uses the turbo to exhaust and vent the heat produced so it creates backfire- and this heat will heat is and can be trapped in between the turbo downpipe exhaust and the catalytic converter and can maybe cause the cat. converter to melt. Now, the waste gate is suppose to do that job- but in reality it doesn't and the car can overheat due to exhaust.
Rx7's produce a lot of energy already, but when turbocharged it's next level heat and therefore a lot of heat. The oil flow is certainly an issue but this model has an electronic oil-meetering pump that circulates oil throughout injectors and inside rotor housing so without an issue- making this an exhaust issue not oil issue. The issue isn't oil in this car, it's too much trapped exhaust heat not ventilating out of the catalytic converter.