Ur B version is the better version but could use a bit more work to improve it to perfection, here's what I noticed compared to real life onboard videos of the F2004:
1. Ur exterior sound has no "Doppler Effect" where the car gets louder & more high pitch when it it passes by you.
2. The low to medium rumble could be rougher like "SHR Moddings" & stretched out longer before the high pitch scream kicks in. About 15k-16k RPM should do it before the high pitch kicks in.
3. The high end pitch isn't as accurate as the real thing, the kunos version of the high end is much more accurate but not there yet.
4. Ur downshifts needs to be a bit more rougher like the real thing
Here's some videos links of the F2004 for reference
1.
https://youtu.be/tU12GSTD9rY?si=Oc9IRw52RILFfmct
2.
https://youtu.be/m8mgAXhNNPo?si=V3OLVIj9g8242cme
3.
https://youtu.be/qGDMyqz3kdo?si=tHrlpkpaZHecv4sM
4.
https://youtu.be/dkrudXgt3O8?si=Jzshb71GjynE_h5H
5.
https://youtu.be/gLyqoX3LZrk?si=b9GMERnbINh8PLGs
Apologies for the long review cuz I genuinely think you can perfect it cuz ur version is like 80% accurate. It just needs that extra 20%. I would love to perfect it myself but I'm no sound engineer. Thank you for ur hard work.