Just the responsiveness of the turbo (no lag now) is worth it. Good luck seeing any gains on the dyno with a 2.25" system. My opinion is that these companies KNOW for a fact that a 2.25" system is going to work with no problems... with no engineering on their part because well, frankly.. if it's only slightly larger diameter piping than stock, how could there be a problem? Even the engineers at Scorpion told me that I could buy either their 2.5" or 3" system, but the 3" was "the way to go" for maximum performance and sound. Why would they tell me that if they manufacture and sell both diameter exhaust sizes? People that settle now for stuff that has been rushed to market will end up being very disappointed. The UK spec cars have been out for a full year (they have had 2013 model Fiesta ST180 out for over a year now) and in the US the car is just now gaining traction in the aftermarket.
Keep in mind, trying to compare a normally aspirated vehicle to a forced induction vehicle (or even turbo v.s. supercharger) is like comparing apples to oranges. The MAIN advantage to larger diameter piping on a turbo car is reduction in turbo spool (or lag). Less lag means more torque at lower rpm and increased drivability. I love how my car responds to part throttle input now just driving around town... the turbo is a LOT more responsive at any given rpm.
I do believe the 03 cobras are supercharged.
Yes and the biggest restriction on this application is 1. The down pipe bottle neck and 2. the cat.
The 3" exhaust system is a significant difference that I hope shows up on the next dyno session.
Let's just say your experience is different than mine.
Throttle response on a turbo car is dictated by back pressure. Less back pressure = less turbo lag. At lower rpm, the actual turbo wheel can actually be a restriction to flow until it starts generating boost. The down pipe on this car is a HUGE restriction (it bottles down to what appears to be golf ball size hole on the back side of the cat). 2.5" or 3" is not going to really make much difference until the DP is replaced. lol It's easy to understand how larger than optimal exhaust pipe diameter would negatively effect a normally aspirated engine due to sonic sound wave and cylinder scavenging (louder doesn't always mean faster either on a fuel injected car, which often times actually needs back pressure to run correctly). However, turbo cars don't exactly work like that. According to Scorpion, the difference between the 2.5" and the 3" Scorpion system is approximately 6 hp (peak) on a STOCK Fiesta ST. Since my car is not stock, I can't say what it does on a bone stock vehicle. I do know they engineered and released the 2.5" system FIRST and found they could go bigger without any compromise. That's why two systems exist, but not for the reasons you suggest. However, I do know this: with an OTS stage 1 (93 octane) tune and a drop in filter, performance increase is something I can feel, not only on my back side but also in the steering wheel. The lack of traction (and copious amounts of torque steer that did not exist prior) in 1st and 2nd gear (despite having sticky 215 width tires) indicates the car is making plenty of power, even off idle. Increased throttle response, decreased lag, better pull. Only a dyno test away to seeing where a negative on this mod exists. It's fun to "speculate" on mods (based on other cars owned ect ect), but I actually have an aftermarket system on my car, have put 300+ miles on it since the install and will have dyno tests done before anyone else even has a named brand system on their car. Anyways... only time will tell what is best for this platform. I can say without a doubt that there is absolutely nothing wrong with a 3" system on the 1.6L ecoboost. How will it compare with a 2.5" system? No use in arguing about something no one has an answer to... yet. Go baseline your car, buy the 2.5" system and test it. I will be putting mine to the test this coming week and will share those results with everyone.
Well, I asked them that very question this morning and this was their answer: The reason we have 2 systems available is that when we originally developed the exhaust for the European market the 2 ½” was deemed to be the best option as we also get the exhausts homologated (EC approved). To achieve this the noise has to be within 2 db of the standard exhaust and you can’t show significant power gains. After we had developed the 2 ½” system tuners also started asking for a 3” system to allow greater scope for higher performance tuning so this is what we have done. Kind Regards
