How much slower would my car be if i put the T5 with my stock 2.73 gears? Will i notice a big difference in my Off the Line?

 

You won't get much pull in the lower tranny gears, but you may get better mileage.

You will also have to swap speedo gears to show correct speed.

 

But will there be a noticeable differnce in how much slower it will be?

 

I went from the stock rear (3.08) to a 3.42 and I noticed a difference. You are going pretty much the same difference the other way (smaller) so you will probably notice a difference too.

My guess off the line would be about .2 slower