The G8x M3/M4 is arguably superior in every category to its predecessor but in most, if not all, circles the biggest downfall of the platform is in the sound department. Like the F8x before it with the S55, the S58 in the current generation leaves a lot to be desired. While a step in the right direction from its forerunner the stock vocals still carry far too much rasp that do not fully articulate the refined aggressiveness typical of the brands signature performance models. Dinan corrects this weakness with a valved axle back exhaust system that elevates the tone to a deeper, more meaningful note while also delivering an extra level of amplification above and beyond its stock counterpart. Coupled with the optional middle exhaust / x-pipe for the platform an even louder, smoother, and fuller soundtrack is possible. Through extensive development and testing nearly every possible permutation of the exhaust was attempted. Unlike the previous generation where cabin sound/drone was largely unchanged between the sedan and the coupe, that was not the case with the G8x chassis’. This caused countless iterations to be attempted in the quest for a common system that not only sounded superb externally but one that also didn’t introduce an overbearing internal cabin drone on either body type. The result is a system we are confident will be coveted by all for years to come. To achieve desired sound volume and tone worthy of the G8x M3/M4 the tubing was enlarged to 76mm (vs 70mm stock) to allow freer flow, and reduce backpressure, throughout the entirety of the system. The larger piping gives way to multiple pathways as it nears the rear of the vehicle — the choice of which is utilized determined by the factory exhaust valves which are retained. When valves are closed, flow is directed into the Dinan muffler, where absorption and reactive technologies are used, and exit out the two inner tips. This limits noise during low-speed driving and produces a more subdued, albeit deeper, and agreeable note. However, when the valves are open during high-load conditions the bulk of the gases bypass the muffler altogether for a near straight pipe design and maximum aural enjoyment to be achieved. It’s the perfect marriage for all tastes and allows civility or impassioned aggression depending on what the situation demands. The combination is one Dinan has deemed fitting for the marques signature performance models that cater to the tasteful enthusiast who demand the best for all situations. Visually, the Dinan G8x M3/M4 exhaust has been skillfully crafted entirely out of T304 stainless steel and TIG welded for the best visual appearance and color. The entire system is then brush finished to further guarantee an immaculate looking system out of the box. The attention to detail is not limited to parts of the system you can’t see once the exhaust is installed but is also extended to the exhaust tips themselves. The Dinan exhaust includes massive, quad 4.5-inch (114mm) clamp-on, double-walled, black ceramic coated clamp-on tips and laser engraved exhaust tips. Despite the seemingly cartoonish size on paper, the tips mesh seamlessly and fill the factory cut-outs to complete the OEM+ look with a healthy dose of audible attitude.