Aftermarket HU, ditch the amp, and use better quality aftermarket 2-way speakers (any good 2-ways will come with passive crossovers).
If you have a high level of "inherent ambient noise" in your 986, you should take better care of it. Even with my loud modified exhaust, the stereo can easily be cranked up to surpass it.
The stock amp is best recycled for scrap.
