like changing the sound of the exhaust to ex. Ferrari,Pagani, Audi,Mercedes,Lamborghini,Porsche, Jaguar and others
it will be nice to be put on to the game to be more unique that it already is . if not can it at lest be and expansion to the game. 
Why? 
Well, the different cylinder configurations, exhausts, intakes, cam profiles etc. do change the sound of the engine, is that what you mean?
no if you look at Porsche carra gt it has a high pitch tone and lambos and other high power cars check the vides in youtube for stock exhaust revs you will see what i mean and it will be nice to have a tone and pitch chart in the game because is something within de exhaust
i believe it is tied to what Daffy said, although exhaust tuning would be an awesome thing… i remember 1 Audi having a spark plug of some sort in the manifold, when you shift, it makes a burbling sound which makes you melt in soundgasm
true i hope daffy sees what i mean but the sound you said your right
Well, the reason a Carerra GT sounds like it does for example is due to the cylinder configuration (V10) The openness of its intake and exhaust systems and how many rpm it does. A BMW M5 or Gallardo V10 sounds very similar at the same RPM, despite a slightly different firing order for the BMW (as far as I know). The Viper V10 sounds a little different due to its firing order and lower RPM though, but still pretty similar.
All flat sixes sound pretty much the same, put an unmuffled exhaust on a Subaru and a Porsche flat 6 and run them at the same RPM and you would find it very hard to tell them apart.
I don’t know what design option you’re asking for here, as sound really is a product of cylinder configuration, intake and exhaust, there isn’t really any other sound related design choices I can think of adding.
so why it’s sounds like a NASCAR motor is because of the cylinder configuration, intake and exhaust i even put the right settings and rpm because i was trying to make a ferrari f430 type engine sound but it’s sound like a NASCAR witch is pretty odd. 
Try flatplane V8.
okay i will tryout the faltpane V8 and see if not i will come back with the results if it work or not
Yep, flatplane crank v8s sound very different (high pitched, similar to an I4)