There's a chap in 'Readers Rides' who has carried out some top notch work to a S1 XJ6, the car appears to be a cherished 1970 XJ6 but he's shoehorned a load of demons under the bonnet. With a huge amount of work he's modified the car to run on the AJ16S engine. The XJ6 4.2 litre was no slouch in its day and can still keep up with modern traffic comfortably but when this fat bottomed old gal hitches up her skirts and sprints she'd surprise most people. So why is this relevant to your AJ6 engine noise thread? The AJ16 is what your engine evolved into 23 years ago, the 'S' denotes the supercharger. The noise, well judge for yourself!