325is, Which chip do I have M13 325PC

[sonej4]

I was looking at getting a chip for my 1990 325is, and while getting the numbers off noticed it appeared to have been opened before. I opened the case and there was a chip already installed and the rev limiter is set to 6900.
I have a 173 DME and the only thing on the chip was a white sticker with
M13
325PC

I know I should have taken a picture, but I already put it back in the car before I realized.

If anyone knows what type of chip it is, please help me out.

[sonej4]

How do I know if it has the m20 maf or stock?
sorry for typos, from phone
E30, FA5

[CW325]

MAF:


AFM (stock):

[sonej4]

Thanks. I looked around and googled, but cant find anything about the chip.

Would it be worth it to swap to a Mark D chip?

sorry for typos, from phone
E30, FA5