Among all the exhaust systems on the market, we couldn't find one that would suit our requirements so we built a complete 3'' modular exhaust system for Alfa Romeo 4C from a scratch.
We decided to offer "one of a kind" exhaust. Unique, state of art, hand built and fully modular exhaust system. We believe we have set a new standard for exhaust system on 4C. All the exhaust components are individually built, with highest level of precision a hand can build. Exhaust component angles and exhaust end tips alignment is achieved by changing angles on the V-bands. Every other exhausts on the market, even from the most exotic exhaust manufacturers for 4C, utilize simple, classic exhaust “slip-on" clamps and "bolt-on" tips to get away with build tolerances and imprecision, and the welds are in most cases, average. Do not worry, that is not the case with GMS exhaust system.
OEM 4C exhaust system, is a cost and emission effective exhaust system, but the penalty is performance reduction, mediocre build quality, sound and look.
Stock downpipe with cat on 4C is designed in a way to be the bottleneck. It is right on a turbo, as close to the engine head exhaust outlet as possible and with curves, tight as possible. This causes very high temperatures which means the best possible performance of the cat and that means the least possible emissions. When you start your 4C you can hear a deep, loud sound from rough running caused by extremely high advanced ignition timing, to make the cat heat up as fast as possible. In a minute or so the cat almost glows and the emissions are as low as possible. The factory has succeeded here for sure. Temperatures are high, emission control is superb but of course, at the cost of performance.
From performance point of view, the stock exhaust system, especially downpipe with integrated 800 cell cat is as bad as it gets. High velocity exhaust gases exiting the turbo hit the 90° cat band right away. After that, the 800-cell mesh even further blocks the flow and by now you have killed pretty much all the flow and performance and the worst, the temperatures are as high as possible. Backpressure is immense. With a basic remap you can already hear the turbo fluttering that is caused by the backpressure. Pumping in even more air is simply rising the temperatures in the head, the pistons, the exhaust system in the intercooler and complete engine bay. Regardless the intercooler you put on, the engine map, the turbo you put on, the factory exhaust system simply won't provide nearly enough flow for anything above 230hp, let alone a remapped / tuned engine, yet it is perfect for stock engine if low emissions are the main goal.
However, if you are looking for the performance than look no further. Everything starts right here with the GMS downpipe. Hand built, TIG welded 3" downpipe, 15 pie cuts perfectly curved design provides all the flow your 4C will ever need for pushing up to 450 HP without worrying of exhaust system being the bottleneck. Drastic temperature drop in the engine bay and turbo and least possible backpressure in the exhaust system. Engine stability on the track is immensely improved and lap times and Time Attack Italia championship podium trophies prove that.
GMS 3” downpipe is part of a fully modular GMS 3'' exhaust system and can be combined with all the other GMS exhaust parts you need.
 
Next step is GMS 3" 200 CPSI Cat or GMS 3" Decat.
 
Next step is GMS 3" 200 CPSI Cat or GMS 3" Decat.