I have my mind on a new traxxas rustler VXL and i am wondoring if the top speed is 70mph out of the box or not? thanks if you can help!
Not out of the box. You'd have to get a LiPo battery as well as change the gearing.
a 3s lipo battery...
Ya can't polish fertilizer...
As far as 70 mph, theres no good answer on that. A good starting point is to get a decent 3s lipo, 5000mah and 40C. Also lower the car so it sits 1 inch from the ground, and add some weight on the front, like 8-10 oz (Draven recommends 6 oz for vxl application). This prevents the car to catch air and blow over at high speeds. If you look at videos on youtube, most of the people that hit 70 mph have their rustlers lowered and some kind of weight on the front. Use 31t pinion and 76t spur. The more weight you have on the front, the longer distance you need to hit top speed, and the more powerful lipos you need (to prevent power loss under heavy load). How ever the more weight you have on the front, less likely are you to blow over due to front end lifting.
How ever you may hit 70 mph all stock with 3s battery, but it wont be safe. Doing speedruns occasionaly you can manage with a fairly stock rusty, but building it only for straight line takes some time and money.