Good god, this is really getting quite old.
As previously stated, no two engines are going to behave exactly the same. ESPECIALLY when forced induction is brought into the equation. Does your engine have EXACTLY the same mileage on it? Has it been driven EXACTLY the same as his has been? Did you change the oil at the EXACT times that he did? See, there are many things that can change the performance just in daily maintenance. Not to mention small variances in the parts already on the car. How about suspension? Tires? Driver skill/ability? Traction parts? Is the temperature going to be exactly the same as when he ran his 13 sec. quarter mile?
Theres just simply too many variables man, but go ahead and use a tune that was made for someone elses car. Be happy with knowing you COULD get a little more out of your car. Thats what causes failure in this hobby, taking shortcuts. Take your time, save up for a real tune from a real person. This coming from someone who has run his car on a tune that wasn't even close to what it needed to be, a tune that was somewhat close, and a tune that was done on a dyno. You need to get that thing on the dyno when your done. End of discussion.