1) First! rename the old file in Dirt > cars > models > 037 > bundles
4cyl_na_sc_037_dd.bdl to 4cyl_na_sc_037_dd.bdlOLD
2) Place the new file in Dirt > cars > models > 20b > bundles
This sound is actually from peugeot 306 maxi, it's a car i don't really use that much but got pretty good sound and it fits 037 kind of well.
Lancia 037 Alternative sound 1.22
Lancia 037 new motor sound