gear swaping??

GEAR SWAPPING???

OK, I have a 99 cobra with the normal bolt on's, but I'm just soo sick of the sleepy 327 gears...(first gear goes by soo soo fast, but then 2nd and 3rd and so on just seem to take hours to wind up!)I want to put in some 373 but I am nervous about doing the swap because I cannot do it on my own and everyone keeps telling me how expensive it is to do on a cobra with IRS. How much is the right amount to pay for labor and what other stuff would need to be installed to make this all work? I am also on my 3rd t45 tranny which are a joke for any cobra owner, But my point is with that...will a higher numeric gear ratio put more stress on my tranny or rear end, because I know some people here have complained about breaking the IRS. Basically my car is a total daily driver and I don't want to worry about breaking any more things on the car than I already have. Realistically is the only trade off with a gear swap, worse gas mileage, because if thats the only problem, well then there is no problem at all

Thanks alot guys... I just don't won't to put something in my car that may shorten the life span of such things as the engine and transmission, although Im not too worried about hurting a naturally aspirated DOHC. They are built to rev. Just a random question to throw out there...because my transmission place was telling me that I do lots of damage to the tranny by shifting at high rpms even if you do use the clutch properly...How true is his statement becuase Ford told me that it is usually too much horespower or tourqe that destroys a trany or long burn outs and stuff? But a regular old 320 horse mated to a t45 seems like it should work just fine, because after-all Ford did chose that tranny