Do a search....only certain 6.5's will fit without modification.

This confuses me. A speaker with a round mount flange of 6.5" diameter, will that fit?

What is the spacing of the mount holes of the original BMW speakers?

The OEM woofer is mounted inside a plastic tube. The inside diameter of that tube is around 163 mm. A 6.5" (165 mm) will not fit without modification.

Not sure about the spacing of the mounting holes.

I was referring to the door speakers - the mids, not the tweeters. Anyone help with the actual size of these?

I don't have the OEM sub box.

Planning to upgrade the front door speakers of my E53. In as much as I would love to have the BSW plug and play Stage 1, it'll cost me an arm and a leg (and probably everything else) to have it shipped here. Sorry bsw :(

So, I decided to scout around the aftermarket shops since the recommendation of the folks here are to get a 6.5" speakers. Went to one shop who had MB Quart ESA 216 6". And another with Infinity Kappa 60.7CS 6.5".

What do you guys think? Will any of these work without too much installation hassle?

Is your X DSP or non-DSP?

The Discus will require an adapter ring for the the install. The speakers in those cars are approx 6.25" round midbass drivers. Many 6.5" speakers will slide down into the housing with a little bit of wiggling and a bit of shaving is sometimes necessary.

If you are amping them then you don't really need to worry about the midrange. It ends up being easier to tune the system running a 2 way system. We are working on a plug and play amplifier(stage 2) for our stage 1 customers! Will be ready very soon!