I would say about the same time, although with the power your running you will have to pull the box in the future to tighten a loose flex plate, due to ford not loctiting it's mounting bolts. <br /><br />I recall a high stall will set you back about 1200-1500, and that is machining your old one. But call CMS or your local tuner for pricing.<br /><br />Do XR6's come with lsd's? If not then you will want a try trac in the future aswell. So you could end up doing both jobs.<br /><br />The high stall will also put more load on your driveshaft, where diff gears won't affect driveshaft load at WOT and anything under WOT there will be less driveshaft torsional stress. <br /><br />Depending on the size of your wallet, will depend on what gears you want, I would go the high stall to keep fuel consumption around normal. And 3.7:1 if your wallet is a little thicker, 3.9 if you like getting 400km per tank of fuel while cruising and like frying tyres almost instantly on take off