sori 4 chipping in...juz 2 share my little know-how in audio (not car audio, but learned a bit of this when DIYing tube amp n speaker for home audio setup).
Add capacitor/condenser in series to tweeter as high pass filter to cut-off low freq (bass).
Add resistor in series to tweeter to drop the voltage supplying to tweeter, hence lower the volume as well as ringing noise. Do not add resistor in parallel, it may burn your amp output.
Adding resistor in series will make your amp to drive harder. Infact, this is what passive Xover circuit does.
Try using non-polarity capacitor (brand Solen, Wima MKP, MusiCap, Bennic, etc) for their sweet/transparancy sound character. If u intend to use a 47uF cap, then get two 22uF and parallel them as replacement. This could cut-off low freq yet less effect on reducing the dB level since the resistance of parallel cap are roughly 50% lower than single piece of 47uF. Besides, this improves transparency. If possible, use silver wires for tweeter...very sweet and clean sound. Try not to use wirewound resistor, sounds dry n noisy. Try to use carbon type (brand Riken).
BTW, I m frm Seremban, Tmn Duyung. But working in Singapore. My bro is a mechanic in Senawang, driving Wira with turbo-charged engine. Mayb u know him. Hope u don't mind I 'kaypo' here :)