Selection of door speakers
 

I have done several attempts to improve sound quality in my 986 sound system. Almost every “upgrade” has made it worse. At the moment a 996 cabriolet amp connected to a Becker stereo. Some new front speakers and the old original papercone speakers are back in the doors. The 996 amp was said to give better bass sound and that might be correct but not with my current speakers. I found some 5.25 subwoofers but they made it even worse than stock.
What if I completely scrap the OEM Amp and rely on a new Continental radio with 4x40 w output and connect to some new door and front speakers. Should I still have subs in the door or will it be enough with any decent 5.25 speaker, type Alpine or similar.

Ditch the factory amps, run full range dash and door speakers off or your new head unit, and put a Kenwood KSC-SW11 Compact Powered Enclosed Subwoofer or similar compact sub in the passenger foot well or behind the seat.

You need the sub to get any mid/low sound, anything you attempt without it is a waste of time. Thank me later.

Just swapping the head unit from stock to a Sony Double Din unit made a big difference. Honestly, it's good enough as is right now. I'd rather focus on some other upgrades since the improvement in sound was so dramatic with just the new head unit

Do you still have the standard speakers installed and is this with or without the original amplifier?

My setup is pioneer single din HU with Alpine amp. I use the amp to feed 6.5” door mid woofers and 3” dash and a channel into a 8” sub made from a 911 cabriolet footwell bose sub bix i modified. Tweeters are powered by the HU. The HU handles cross over between sub, mids and tweets and the cross over on the amp handles cross over between low mid and upper mid freqs. Sounds pretty good.

Paper door speakers? You sure? I've only ever seen poly cones in the door subs, other speakers were paper at some time in their lives. If you plan to change to 2 or 3 way speakers in the doors you may be disappointed with the results if you don't replace your Haes (4X40 or 6X40) amp. Those amps both have an internal low pass filter that chops any signal above 50Hz going to the doors, so those speakers won't get anything but low frequencies. If you're handy electronically, it has been written that the solder connections for the filters inside the amp can be undone. IIRC there is a write up on Rennlist. BTW, I kept the factory subs and replaced my Haes 6X40 amp with a 5-channel amp (I have the rear deck speakers). The two 5.25 door subs (wired in series they have 1 ohm resistance) will provide significant bass response, plus just think of all that fancy German engineering in the door card horns.