Tyres are pretty decent, worn 50%, no nos, no water-meth.Haven't been on a dyno, going to book it in a week or two. Its also very hard to drive in a rain, car behaves like im driving on ice... And i have 2.56 rear diff ratio, not 3.31 like xkr.

 

Xjr- that sure is a tall ratio on the diff

you surely must be getting close to the upper torque limits of what the zf is capable of with standing now

 

It's not even XJR, it's LWB XJ SuperSport (with 6hp28 tranny, lol). Pretty heavy saloon with a lots of stuff in a trunk and almost always with 1/2 or more tank of fuel.
I've changed tranny oil 20000km ago, no metal shavings, no dust, oil was pretty clean, so the 6hp is pretty robust and can live with pretty high torque figures.

 

Heavy Duty ZF Input Shaft - Nizpro Turbocharging

Food for thought these guys make billet input and intermediate shafts for the zf6hp have a feeling might be useful for your application !!

 

Well, since im going to put semi-slicks im more warried about a diff and driveshafts, but... I have a spare new ones, so at least i'll know a borderline, lol)

 

I just recently went back to 3.31 from 3.58 (gen2) as my diff exploded !!

 

2.56, don't see a reasons to go 3.31, with 2.56 2nd gear ends at 110kmh, which is handy

 

Having boost and tall ratio works fine, no boost like me I need plenty of rpm & short short ratio to try and get some kind of performance from the car .still wait for prices of 5L xjr to drop in Australia

 

Where did you get 2.56?

 

Standard ratio on xjr

 

🤦🏻‍♂️ Yeah, I read that not sure why I thought he was referring to his XKR