When you use normal incandescent bulbs for turn signals, and one blows, the S2000 will hyper-flash the remaining bulbs to highlight to the driver that a bulb has gone out or blown in the circuit. This is the same for most cars. When you switch to using LED bulbs which have a much lower power consumption, the S2000 will start to hyper-flash all the indicator bulbs during normal operation which is undesirable.
The established or traditional way to fix this issue is to hack your wiring loom and solder or crimp in to the wires a bunch of resistors to compensate for the lower led bulb power consumption. These resistors get hot so you have to be careful where you fasten these to your cars interior to avoid any burning or fires.
Here is my fix for the problem of hyper-flash when updating your bulbs to LED's. The much cleaner way is to simply replace your flasher relay for an LED capable flasher relay. This then means you can mix and match the type of bulbs on your S2000 without the need for resistors and messy wiring. The LED flasher relay will work for normal incandescent bulbs and LED bulbs, so you can replace the bulbs one stage at a time.
I have done my research and found that some of the LED relays are too large to fit in the S2000 fuse box. There is however a relay which fits nicely and will solve your issues with hyper-flashing. It is the CF15-JL02 LED Flasher relay.
Step 1. Find the indicator flasher relay in the under dashboard fuse box. Black square box in picture (non OEM shown)
Step 2. Using 2 small thin flat screwdrivers carefully separate the clips on each side of the relay at the same time to allow you to extract the OEM flasher relay. Its fiddly, but I managed it in about 10 minutes. Some have really struggled with this step. The secret is to get one side un-clipped and leave your screwdriver in place whilst you un-clip the other side. If you try to release one side then the other, it will pop back into place each time. Be patient.
Step 3. Pull out the OEM relay and keep as a spare.
Step 4. Insert your new CF15-JL02 LED relay into the 3 pins in the fuse box.