Debating trying some 6.5" tri axials with this headunit....

Unsure whether I'll run into issues

 

With the kenwood excelon x-kdc998

 

I got an Alpine CDE-HD138BT and noticed a significant improvement in sound. I was considering changing out the speakers before as well, but I am satisfied with the sound to not do anything about it.

 

I just purchased a 2002 s2000. I would like to make upgrades needed so that I can send music to the system from my iPhone via blue tooth and also so that I can place and receive telephone calls from my iPhone hands free using the radio. I would like to be able to use the stock dash controls to control the radio/player. I want to avoid any changes that will not be reversible so as to preserve the "stock" nature of this car which is in virtually mint condition with just 8.500 miles. What is the best way to accomplish this? I might also consider speaker upgrades in the future but not right now. My plan is to have my iphone mounted in a cradle powered by a cable and connected to the radio via Bluetooth.