http://beepshift.comMany races are lost due to shifting to early or hitting the rev limiter. Beep Shift will help you shift at the right time and play the beep though your car sound system. You adjust the volume and pitch of the beep.
With beep shift you select the RPM that you wish for your phone to beep at and when you hear the tone it is time to shift. It is an extremely easy app to use. The app works even better when you use bluetooth or a line into your cars audio system to make sure that the beep tone is loud and clear. NEVER miss a shift again with beep shift.
Below is a link to a communicator for the app:http://www.amazon.com/gp/product/B00OXPXUAK/ref=pe_385040_127745480_pd_te_o_gc_im/187-2523161-4635036
Feel free to use ANY ELM327 device.
Works on any vehicle that uses the OBD 2 standard (most vehicles built after 2000, but can work for vehicles as far back as 1996).