finally installed the 1.5lb pulley on an otherwise stock 2008 XKR vert
In everyday driving there is a noticeable difference in responsiveness of the car, so just for this benefit the mod is worth it.
I also happen to have 1/8mi times before and now after to compare before and after

now this was done at different tracks thats why corrected times for density altitude should be used instead of uncorrected time slips
best 3 runs before the mod :
8.56 (1.95 60ft,83.17mph),
8.58 (1.93 60ft, 82.59mph
8.61 (2.02 60ft, 82.18mph)
avrg Uncorrected 8.58 (1.94 60ft, 82.64mph)
avrg corrected for supercharged engines is 8.49 @ 83.516 MPH

After the 1.5lb pulley install
8.50 (1.91 60ft, 84.23mph)
8.51 (1,93 60ft, 84.39mph)
8.52 (1.92 60ft, 84.39mph)
avrg uncorrected 8.51 ( 1.92 60ft 84.33mph)
avrg corrected for supercharged engines 8.382 @ 85.603 MPH

Even though when I ran at the track after the mod, I didnt think that the pulley added anything to the times, but after using correction factor for density altitude I think its safe to say the the pulley does gain some hp.

 

I presume both runs were with the stock factory tune. Will you add a custom tune?

 

No tune , No other modifications

 

Alex with a custom dyno tune along with a x-pipe in place of the front resonator im sure you'd see hefty gains

 

Custom Dyno tune is spendy around $1500 not sure that I want shell out that much cash at this time. I wasnt aware that removing the resonator will add any benefit at all other than sound..
I am contemplating High flow cats though.

 

It is unlikely the x-pipe will do much for power gains. The pulley probably added between 5-15 HP/TQ. A remap will give you the most benefit, not just with numbers on paper but also with the behavior of the motor and transmission and also adjust blower boost bleed off, which your car is now doing since boost is outside OE spec.

See my tune thread here: https://www.jaguarforums.com/forum/x...o-tune-164787/

 

Thanks Jahummer
I sent velocity an email to see what they would offer for a tune