This is my 1/16 AC Cobra 427, built from an Airfix boxing of the old MPC kit.  Although large in scale, the kit is not the most detailed.  I've added engine wiring & brake pipes from fuse wire & also converted it from left hand drive to right hand drive, which largely involved turning the dashboard over & detailing the rear face of it.
The biggest problem with the kit is the wheels & tyres which are absurdly over-wide, the rear tyres being some 18 scale inches wide & the fronts 12.  Fortunately the tyre tread consists largely of circumferential grooves, which allowed me to narrow the tyres by cutting off one sidewall, removing a portion of the tread & superglueing the sidewall back on.  I narrowed all four wheels, fitted the original front tyres to the rear & the rears, narrowed by over half their width, to the front, which greatly improved the look of the finished item.
The bodyshell came with cutouts in the lower front fenders for the sidepipe exhausts to exit, but I wanted to fit tail exhausts, so had to blank off & fill the holes.  Also, the tail exhausts were intended to be fitted to simulated cast iron exhaust manifolds, but I wanted tubular headers, so I modified the sidepipes & their headers to exit under the car, cut them short & fitted the tail exhausts to the ends.
After much rubbing down to remove the evidence of a previous abortive paintjob, the body was primed & finished in Austin Rover Flame Red using automotive aerosols, left for a week & then flatted with 1200 grit wet & dry, polished with automotive cutting compound & waxed.  The remainder of the paintwork was Humbrol enamels.
John