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. I believe we've set a new standard for exhaust system on 4C. All the exhaust components are made to the highest precision, hand can build. Each component of GMS 3'' Modular Exhaust System is built on a prototype jig, so there is no difference between yours and your neighbours 3'' GMS exhaust, except the loudness, depending on your component selection. GMS 3'' Modular Exhaust System consists of 1x stock + 3x GMS QR V-bands. Exhaust component angles and exhaust end tips alignment is achieved by changing angles on the V-bands. So far, until now, each and every other exhaust on the market, even the most exotic exhaust manufacturers for 4C utilize simple, classic exhaust clamps with "slip-on" system and "bolt-on" tips to get away with build tolerances and welds are in most cases average. Do not worry, that is not the case in our exhaust system.
When you look at the stock 4C exhaust system, you quickly notice a strange, unappealing design, starting with tight downpipe and integrated 800 cell cat. Now there is always a bragging about how good the aftermarket part is over stock part, but there are few things we need to know and respect. By more and more demanding ecology standards, there is no secret that today’s cars are taxed according to the emissions they produce and manufacturers struggle to get the best performance with least possible emissions and ecological impact. Between these two factors, there is always a trade-off. It is either performance or ecology.
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, yet it is perfect for stock engine if low emissions are the main goal.
If you are looking for the performance than look no further. Everything starts right here with the 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 exhaust system in the turbo and least possible backpressure. Engine stability on the track is immensely improved. Lap times and Time Attack Italia championship podium trophies prove that.
This is part of a fully modular GMS 3'' exhaust system and can be combined with all the other GMS exhaust parts you need.
ALFA ROMEO - 4C - 3'' Downpipe
- Lightweight 930g.
- Plug and play.
- Compatible with stock turbo and hybrid turbo.
- 3'' / 76mm diameter.
- 14 pieces of pie cuts for highest possible flow design.
- Back purged TIG welded.
- Quick release V-band clamps for easy installation.
- Heat sink designed oxygen sensor port.
- T304 Stainless steel.
- Less engine heat.
- Less backpressure.
- Less turbo lag.
- Better throttle response.
- Faster gear shifts.