Passive Crossover for JBL GTO426

I use JBL GTO426 4" series speaker on my car. It's coaxial speaker, with affordable price and high quality material (not high quality sound). I use GTO426 because i dont want to see tweeter above my dashboard. And GTO426 mount perfectly on Suzuki Vitara dashboard speaker mounting. Sound quality is far from great, not even good. Middle sound is very weak, high frequency sound from tweeter is not sharp. Mostly i play Metal, Heavy Metal, and other song that have heavy guitar distortion, like Metallica, Megadeth, Linkin Park, etc.. The GTO426 unable to reproduce that heavy sound distortion from my Alpine HU. My decision is to look at the speaker and add passive crossover for woofer and tweeter. I think JBL make very good product, so i am sure their product have better potential quality. JBL GTO426, using small capacitor 3.3uF/50V as 1st order high pass filter for tweeter. The capacitor is made by well known taiwanese audio grade capacitor manufacturer, Bennic. From that value, i know the tweeter have cut off frequency at 6000hz, and i use this as initial value for my 2nd order passive crossover. From my calculation (I use Linkwitz-Riley equation for first time) i will need 1.65uF capacitor and 0.42uH inductor, both for LPF and HPF. First, i build on prototype pcb, or known as "PCB Bolong-bolong). I use "most bang for the buck" high performance capacitor made by Solen with capacity 3.3uF in series for HPF, and 0.47uH inductor which is closest value available on "Pasar Genteng" electronic market. For LPF i use lower grade capacitor made by Bennic with same value. The main concern of this modification is price, so why i spend 1 juta rupiah on 500 ribu rupiah speaker. Result is very significant. Middle frequency sound is better, but, high frequency is to sharp and bright. First test, i play Jack Johnson - Better Together, sound detail is good, i can hear detail from guitar string, but high frequency sound is too sharp. Second, i play Megadeth - Angry Again, the sound is more crunchy, vocal is more clean, and instrument layer is more detail, but cymbal sound is very sharp. But overall result is good. After some inspection, i found that inductor value is not consistent on 0.47uH, one inductor is 0.49uH, and three inductor between 0.46uH and 0.47uH. All of them need some minor value correction, so i done that, and have 0.42uH. And sound test result is more better. High frequency sound, is not too sharp anymore, middle sound is more powerfull and crunchy. This "100 ribu rupiah per-ch crossover" is satisfying, sound from JBL GTO426, is very crunchy, heavy and details, i dont know what if i use lower frequency cutoff, or higher. Maybe better ?