Rear speakers recommendation to fit 2 door 316?

[cgt]

Hi, hope someone can help. I have just bought a 316 2 Door (1990). I've upgraded the front speakers and head unit and put tweeters on the dash corners, but the speakers I wanted to put on the rear shelf are way too big and cannot be mounted on the shelf because of the two rods running on the underside.

Sounds are very good with front speaker upgrade but I do need to put some in the back to get a proper soundstage. Can someone recommend some please?

[Kos]

any decent 5.25"/13cm speakers will fit and work well

the likes of infinity are good with out being too expensive.