currently I have a vitara build d16z6 T3 50 trim.
I currently have a S20 long gear transmission.
Would i benefit from going to a shorter gear Si tranny?

I think my rear main seal on my transmission in currently going and thus causing motor oil levels to decrease gradually.

 

The only time longer gears are better is when your gearing is too short to reach a max speed in a certain distance. IE, if you're topping 4th before the line.

Other than that, you will ALWAYS benefit by going with the shorter choice of gearing.

 

In your case you will benefit from the Si trans.

 

ok
so for 255whp and 208lb ft torque an Si tranny will do fine?

can i get an EK tranny? which code will an EK SI tranny have?

 

A D16z6 ex/si trans has the same gearing as the D16y8 ex trans. I believe the general code is S20, but do not remember how to distinquish between a CX,DX, ETC. I rebuilt a CX transmission and the code on it was S20 also.

 

To ID : Look by the fill plug. You'll see a circle cast into the housing.
P20-A000 = DX,CX,VX trannys
P20-B000 = Si,EX trannys.

 

There ya go.

 

Right now I have a long geared DX or VX not sure which exactly.
Will the SI make the car feel much quicker?
I am a d16z6 boosted setup.

also, I have an option to take the shift linkage with the transmission I am going to buy. Should I replace my old shift linkage with the 1998 one?

Also, would this incur a lot more labor when swapping out my current transmission with the Si tranny to have the shift linkage changed as well?

 

You have to disconnect the shift linkage from the tranny anyways when you swap it out but if your bushings are fine then you don't need to switch it. It's only 3 more bolts though if you're dead set on it.