It depends on the gearing in the T5 if you just get a stock WC from a mustang with the 3.35 1st gear then its not really worth it. With 4.11's and that gear ratio you can start out in second easily and the maximum speed of first gear is around 16 to 20MPH depending on your tire size so you will almost have to do an immediate shift to second. Or the other option is to just not use first gear and start out in second instead because the rear gears would be low enough you could probably get better performance doing that with the 1.99 second gear, which is just a bit higher then the 2.40 first gear in the C4 but probably suited really well to 4.11 gears. One thing you have to remember most of those T5 transmissions were geared to run with factory 3.07 gears in the 8.8 rear end and that is what they are suited for. With the factory T5's gears of 3.35, 1.99, 1.33, 1.00, and 0.68 you would be better off holding the maximum gear ratio in the 3.30 to 3.55 range to keep first gear useable. Now if you went aftermarket gears on the T5 like the g-force gears that cost an arm and a leg but utilize either a 2.95 or a 2.42 first gear ratio then 3.70 or 4.10 gears might be better suited for that transmission.
so lets say i drop the t5 and go with a 6-speed, would tht be better siuted to handle tht rear setup of eithr the 4.10 or 4.11? tht way i wouldnt have to go through a tranie rebuild
Tranny rebuild might be easier then a possible transmission tunnel replacement. Six speeds are big fat and long transmissions and some of them require all sorts of special stuff to work with your motor. But you need to look at what six speed and decide which one you are going to use. The gear ratios are the biggest thing, the Tremec T56 has two different ratio setups one similar to a standard T5 with two overdrive gears one being a .8 and .62:1 ratio and one similar to the gforce gears with the same two overdrive ratios. The tremec T56 is a very pricey transmission new they are in the $2700 price range http://www.summitracing.com/parts/CMG-TUET11011/ oh and the richmonds are the more expensive of the six speeds they start out in the $3300 and go up from there http://www.summitracing.com/parts/RMG-7041626AC/ From what it sounds like you are dead set on the 4.11 gears maybe you should look into a tremec TKO600 they have the first gear ratio that is more beneficial to the lower gears, they will accept a higher horsepower rating(stronger then the T56, and my TKO). Of course they are about a $2200 transmissionhttp://www.summitracing.com/parts/CMG-TCET5008/(not as expensive as the 6 speeds), but they will fit with only minor modifications too your car, they are the same size as my TKO and it fits just fine. But most of all more importantly... You dont need super tall gears like 4.10's if your transmission already does it for you. The gear ratios like in the T5's, TKO's and TR3550's allow you to have performance like 4.11's in the lower gears but allow you to run gears like 3.30's and still be able to go 120 mph without blowing your motor.
this is some good food for thought, thx a lot. i really wouldnt want to go with the 6 speed cause i want as close to a daily driver as i can get. the 4.11's i just heard were good at low idling making them the bettr choice for a high hp engine. but what im most concerned about is getting tht perfect combination of street/strip-ready and daily driver with good mpg's. i know its a long shot but this is what i plan to do with my life: make old cars better than the new ones today.
