I never really played with the Mazda Rx7 i put turbo in it and that engine sounds awsome i cant remeber if it sounded like that in F5 or if thats a new sound.
Do you mean the RX8? The RX7 should be turbo from standard.
Youre right the Rx7 comes with turbo but it is the car that sounds wicked first time ive heard that engine sound
The rotary engines in the RX Mazdas are very different indeed to your conventional piston engine.
The RX7 is turbo twin rotor and the RX8 is naturally aspirated twin rotor, so you’ll probably like that too. I loved the old RX3 in Horizon 1.
Try out the 4 rotor twin turbo engine swap too. You should be able to put that into the RX7, RX8 and also the MX5.
Enjoy!
Where did you learn that from very detailed and knowledged on Mazadas,they sound like the TakataDome iam just guessing thats the car tney had a few inGT that looked the same
Complete list of car for the 4 rotor are here:
Includes the Nissan Silvias 
If you’re talking about the sound difference between Motorsport and Horizon, then yes the Rotary sounds great on Horizon but sounds very tame on Motorsport unless you put the 4-Rotor in it.
My favourite rotary swap was the 20B triple rotor twin turbo but with the turbos removed - the engine came from a car that was never in any FM games and was available at least in FM2 and FM3 (not sure about FM1). Didn’t really like the Furai triple rotor that was in FM4.
Stopping before this becomes wishlisty