Ok if you drive a E36 after 95 so 96+ then yes you have to shark it. It is an OBDII car not OBDI. Sharking is basically a software update without the physical "chip". What it does is raise the rev limiter, take of the governor, and give you more hp by remapping your fuel curve. You will have to use 91 octane but the results are actually felt. Check into turnermotorsport.com and dinan they both other sharking. It is a little more expensive than a chip and gives you a little less increase, but check it out anyways. http://www.turnermotorsport.com/html/detai...UCT_ID=INJ3-M20
I have the conforti chip(OBDI) from turnermotorsport.com and love it. It is a big difference and I am very happy with it. You can check the review section to see a bit more of what people think about there chips/software. Also check out the FAQS section and performance to learn more about them.