Google #1 Rank

Simple Project I have a website www dot hondacivicexhaust dot com Currently it ranks around position 3 in google for the main keyword "honda civic exhaust" (without the quotes) however it jumps around from position 1-5 all the time. I need it to stay at number 1. Use whatever method you want but it must be whitehat, this should be simple for someone who knows what they are doing. If you need to do any on page optimization I am happy to let you make small changes to the site. I will deposit 100% up front. You get 50% when the site is at number #1 and the remaining 50% if it is still there after two weeks (14 days). I'm not interested in #2, if you do not get to #1 you will not get paid. If you don't agree to this please do not bid. Please let me know how you plan to achieve this and an estimated time it will take (I realize you might not be able to give me an exact time, just an estimate is fine)