Do not get an e46 m3 under any circumstances. First and foremost, it doesn’t sound mean regardless of what exhaust you have on it. Even the eisenmann race or dixis spirit still make it sound like a chainsaw.
Second north of 100k miles, you’re on borrowed time. Even after the bearings grenading engines (3 of mine) and the service surrounding it, it’s still a crapshoot. You can do way better for 25k. WAY better. You can get into a C4s for the same money with the rms work done and have a better car. I’ve owned and tracked 3 e46 m3’s. I know everything about them. Every nut and bolt. Stay away.