Booked in this morning for a Mod-Stock back box exchange with new stainless aftermarket valves. I’d called at the start of the week and Chris, the owner of Mod-Stock, based in Epsom, Surrey said they’d be up in the North West on Thursday (today), so my timing was perfect!
Drove up to Rochdale to garage premises that him and his team were working from for 9am. I was a little early arriving about 08:30 as I wasn’t sure how busy the traffic was going to be. The guys were just setting up and another V6S, a convertible pulled up behind me. Had the pleasure of meeting Swedish owner Martin and chatting together whilst the guys got our cars jacked up and started work.
They had already modded two V6 back boxes which were ready to exchange. All in it took about 1/2hr, which was fantastic. I was going for the modified back box and new aftermarket stainless valves. I knew my back box had been replaced by the previous owner about 5 years ago, so was still in pretty good condition. However, BOTH the valves had broken shafts/ linkages, so were not operating correctly! I had suspected this as I couldn’t hear an audible change in exhaust note with the switch in the open position. Here are the broken linkages.


Here is the modded back box before fitting with the new, aftermarket valves welded in.
For those not familiar with the Mod-Stock modification, what they do is open up the box from the top side by removing a large patch. This gains access to the resonator boxes inside. They open up the resonators, which have pipes that pass through them which are full of small holes, allowing some of the exhaust gases and sound to circulate outside the pipe in the resonator box, thus creating that tuned exhaust note that the V6 is known for. The guys cut a section of the resonator pipe out and replace it with a length of exhaust pipe without the tiny holes, in effect doing a partial ‘straight pipe’ through the resonator. They experimented with exactly what length was required to give the enhanced exhaust note, but without any droning and unwanted raspiness. They have certainly mastered the correct length!
They then weld the resonator box back up and replace the ‘access hatch’ they had cut out of the top of the back box. The new, much better quality valves are welded in place of the genuine, inferior/ prone to rust and failure original valves, which they guarantee for the lifetime of your ownership.
No re-tune, nor coding is required, and the new valves work exactly as the genuine valves using the centre console switch and/ or Dynamic mode selector. With the valves closed there is no change to the original exhaust note (which will keep my neighbours off my back when I leave for work at 4am!) Here is the box ready to fit and a close up of the aftermarket replacement valves. OMG it sounds magnificent! Extra grunty sound above 3000RPM when accelerating, stronger snorts on the upshifts with higher revs and more pronounced pops and bangs on the over-run with the valves open, quiet as before with the valves shut. One happy bunny.


Here is Mod-Stock’s website. https://mod-stock.co.uk/collections/v6-f-type