i had a '99 chrysler LHS with this motor in it. wow, it was quite a powerhouse for a v-6. and believe me the LHS is quite a bit heavier than the xf. i was apprehensive when i bought the LHS but it was identical inside to the 300 with the same engine. i was so impressed with the 3.5, i think it would make the xf a real rocket but the price would be astronomical. the 3.5 is a very reliable engine as well. i put 100,000 miles on that LHS before i traded it in on a dodge ram hemi. never had the first problem with the engine. did have to replace the rack and pinion ($1,200.00), compressor ($800.00), and ECU ($450.00) but the engine was a gem!!