What device are you using to hybrid with?
What I would do, and have done, is go with the supercharger instead of the turbo. There are three cars running superchargers in the game and they will run fine with the NA engines with or without using the NA tune together with the supercharger, or the supercharger alone.
I have used the Z06 engine with the supercharger and it runs great and sounds great with the racing muffler.
I have a mustang sitting around which I will attach, which is the 67 Cobra engine supercharged with a stock exhaust.
GS2/AR2
1C0413F8 - A04BDDA2 1C0413FC - 712F10A4 Stage 1, v8_vantage 7%
1C0413F8 - A00C68F4 1C0413FC - 29764D3A Stage 1, xkr_coupe 9%
1C0413F8 - C323351C 1C0413FC - 339F50CE Stage 1, slk230_komp 15%
1C0413F8 - A00C68ED 1C0413FC - 29F64D3A Stage 2, xkr_coupe 17%
1C0413F8 - A04BDDA4 1C0413FC - 312F10A4 Stage 2, v8_vantage 41%
1C0413F8 - A00C68EE 1C0413FC - 1C764D3A Stage 3, xkr_coupe 43%
1C0413F8 - C3233555 1C0413FC - 339F50CE Stage 2, slk230_komp 45%
1C0413F8 - C32335F6 1C0413FC - 339F50CE Stage 3, slk230_komp 70%