i actually had my stock gearing heat treated. it wont help much but it was practically free and it will help some. anything is better than stock, i do mean anything. the stock tranny we have has been used in subaru's for years upon years. it even came in a few justy's. however the sti tranny(6-speed) suxxx. 8 grand for only 300 hp reliability? what kind of poop is that?
as for the dogboxes such as mrt or harbinger. those fruitcakes wouldnt back their product. i said i was going to build a 600 hp wrx and they said that they couldnt gauruntee that their box would hold. then i said how about a number about how much power it could hold. i couldnt pin them down on any numbers. they wouldnt commit to anything. then i finally asked if they "thought" it would hold the current power i was making and all they would say is maybe. they bugged the crap out of me. so i said f-- it and put the stock one back in (after the heat treating). i figured i had already acomplished what i wanted. an 11 sec street driven car. i am happy with that.
i am running the biggest top mount on the market currently its an m2 stage III top mount. which is bigger than most of the front mounts currently offered. and a garret hybrid t3-t4 she was made custom for me and flows 673 cfm. ugliest turbo i have ever seen though.
btw: even with good tires on her... i can spin all 4 past my 60 ft mark. and have the video to prove it.