You should go with 5.25" speakers in the front! To do so will require Autoleads SAK-1104 adapters, but it's definitely worth it compared to 4.5" speakers IMO. I found some on eBay for a good price a while back.

 

What is that, an adapter plate that mounts to the door, then the new speaker mounts to that?

 

Exactly.
4.5" speakers won't just bolt up either, as the stock speakers have an integrated mount that is totally non-standard. In fact, I would highly recommend buying the Autoleads adapters if you want an easy front speaker installation.

 

Well the front doors are like the rear doors, they have the three mounting screws, right?

 

My '98 A4 which I've modified the sound system on, the front doors have 3 screw holes. But that car doesn't have rear door speakers so I can't comment on the similarity, other than I imagine they're pretty similar.

 

What?! Some A4's didn't come with rear door speakers? Is that the difference with the Bose? And what do you guys think on a DIY headliner replacement? Mines getting bad and want it fixed, but it seems easy enough to do on my own.

 

Yeah I think it's that non-Bose don't have rear door speakers, only front door and rear deck. My 2001 A4 has Bose and it has rear door speakers (just haven't taken the door cards off yet to look at them).

Headliner is doable, but definitely a PITA. I also replaced the fabric on the sunroof slider, which meant removing the sunroof, and is also a PITA. Have somebody help you when removing/installing the sunroof and your life will be 100x easier.

 

Now obviously if I'm not doing the slider I won't need to remove the sunroof, right? I don't know what the hell happened to my slider, I just found out a couple of weeks ago that I'm supposed to have one!It might be stuck between the roof and the headliner board...

 

You wouldn't need to remove the sunroof if you're not doing the slider.

 

Awesome. Helpful as always, MetalMan. Thank you!