yup in post #7 i agree with what you said in post #6 not really sure where the hostility is coming from unless it just reads that way. if i were to get a 2nd xjs with a v12 700r4 a looser torque converter and gears would defiantly be one of the first thing i did to it.

i think the only thing i disagreed with you on in this thread was if it would be reasonable to keep detonation under control on a street drivin xjs with boost without first lowering the compression ratio.

not my first rodeo eater iv been building cars and turning wrenches for the majority of my life im not a jag expert by any means but not a novice mechanic ether.

i suppose the o/p has not really said what his goals are what his budget is or what his skill level is so we are kinda all over the map on suggestions and different ways to increase performance.

similar design, both are roots style blowers, its a wieand 144 essentially the same thing as a 142 just with Teflon tipped rotors.