As cdmh mentioned same as me going to mentioned.
Yes rev could be due speedo face fitted but if you can hear engine sound quite like normal rev that it problem with gauge.
But best is check on obd computer to see correct rev is running.
As you mentioned about exhaust steam and if you feel car is over rev that is because car is running rich.
Engine on idle rev should be very quiet.
If you feel or hear rev high than that’s not speedo problem but to do something with rich running.
Cheers
As dash vent and rear reinforced bar CDMH already have advised you on that.
Cheers