- May 22, 2022
- Reaction score
- Paisley, Ontario, Canada
- 78 280Z, 76 280Z, 88 300zx
Twin 2.5 will be more than enough.
If you're not trying to optimize, sure.Twin 2.5 will be more than enough.
I guess he's thinking if you're replacing turbos, going full race downpipes and making 1000 HP, it's probably better in the long run for breathing. The cross sectional area of a twin 2.5 is huge. Way bigger than a single 3" setup too. If you can squeeze dual 3's under the car safely and don't mind the added cost, then why not I suppose. But, for the average guy looking for a nice upgraded cat-back exhaust for a mild build, 2.5 is great. The mufflers will end up being the biggest restriction. You might as well chop the downpipe and put in cutouts if you're real seriousExplain
Having developed a wide range of prototype exhaust systems our engineering team hit the dyno to see which configuration produced the best results. After all of the tests were completed, we were a little bit surprised to learn that the best exhaust system was lying in front of us the whole time. The twin turbo V6 Nissan GT-R favors a dual into single back to dual configuration and after our testing was complete we learned that the Infiniti Q60 VR30DDTT does too. This exhaust system features a 2.5” Y pipe which flows into a 3” mid-pipe. The 3” mid-pipe then carries the exhaust gases to the rear of the vehicle where it branches back into 2.5” dual rear exit.
A wide range of testing was performed on a range of different diameters and lengths of exhaust pipes in varying locations of the exhaust system. All of these tests demonstrated different ways of changing exhaust pulse scavenging and backpressure. In all cases the results show scavenging is beneficial and back pressure is detrimental to engine performance. Engine performance can be maximized by utilizing a continually expanding exhaust system design with the smallest (optimally sized) pipes closest to the engine and progressively expanding to larger and larger diameter pipes as the flow moves away from the engine.
- Test pipe performance for NA engines is optimal at 2.00” in diameter, but larger diameters should be used in Turbo engines.
- There was no scavenging possible after the Y-pipe.
- A mid-pipe smaller than 3.00” in diameter can only decrease HP and TQ, however there are diminishing returns from increasing this above 3.00”. Thus, 3.00” is optimum for NA engines.
- Single 3.5” or dual 3” yields the same NA performance but allows more headroom for medium and high turbo boost applications.
Stillen is only saying the style of exhaust works best, not the size. Also, comparing exhausts on a turbocharged engine to an NA engine is like comparing baseball bats to water bottles.
Fast intentions uses a dual 2.5 for their q60 exhaust iirc, which I believe is the highest regarded catback for quality and gains on that platform, which is probably why they're using it for the Z.... who said anything about a single 3"? Of course two 2.5s are bigger than a single 3, that's simple math. Yes, a dual 3 will fit. It will also be more efficient and make more power/torque at ANY power level vs a 2.5. On top of that, the cost alone makes a 2.5 pointless. Hell, even FI themselves say use a 3" for forced induction Zs.
the auto is pretty close to the FI exhaust.I like the FI exhaust - it's exactly how the Z should have sounded from factory.
You'll be happy with the exhaust if you enjoy the VQ/VR engine sound. I had the VQ version, and only made that exhaust upgrade due to the fact that the exhaust sound got deeper (a'la 350z/G35 OEM + sound). Just watch out for the tips yellowing (not sure if this has been remedied since 'the 2016 models). Also only use carwash soap and water to clean the exhaust and some light metal polish to shiny it up.For any of the Canadian guys looking to order this, my system will be in today, obviously no car yet. But I'm totally committed. Wanted to get ahead of lead times just in case there's a huge back log when the cars start to pour in.
As a heads up the total price to my door with conversion and taxes and additional UPS fees (Ontario) puts it at $2758 CDN. It's a tough pill to swallow, but that's the downside of cross border pricey parts shopping. So just a little note as to what to expect if you're saving for an exhaust north of the border
No turning back now lmao