Ok I'm new to the mix and match between J-spec, S4 and S5 parts.
Currently I have a 87 TII (stock) and I need a new tranny so will a S5 tranny be a direct bolt up to my 87TII car. Or can I go the J-spec route and will that be a direct bolt up? Am I correct that I will need to change out a gear on the J-spec Tranny to get MPH to work and is this a hard mod to do if it has to be done?

Also, I'm getting up to 100,000 miles on my engine. So can I just drop in an S5 engine in my car or will I need all the S5 parts to go along with it like ECU and wiring harness?

Any input would be great, and I'm sorry for being a noob in advance!

 

Yes.

Yes. The only difference is the slightly shorter 5th gear ratio.

No.

To swap the whole engine you need the ECU and harness, and it's still a lot of work. Getting a complete replacement S4 engine is much easier, but you can take advantage of most of the S5's improvements by using the S5 core, manifolds and turbo, and swapping onto it the S4 front cover and TB (if you want to keep the OMP), and the EFI system.

 

dont forget to use the weird s4 xmemebr