jam0321

So Mossy Performance is no more (long story) but Greg Vogel who ran the show is starting a new company named G Spec and will be completely operational in the coming months. However, all the same great products and service will be offered and to start things off, Greg is releasing a new line of Lightweight crank pullies.

These puppies are hardened lightweight aluminum (1.1 lbs) They are stock diameter and come only in flat black

Best of all, to start off the business he is selling these for $100 shipped!!!

feel free to give him a call @ 760 535-2259 or email him @ gspec.com

As far as the 3" exhaust goes, it is awaiting final fitment and will by dynoed as soon as I can get it up.
I know there has been a lot of talk on another thread about the 3" causing low dyno numbers and although every tC and dyno are different...I'll soon be able to show everyone the gains, not loses, incurred with this exhaust. Keep in mind, he said it was a "custom" 3" which could mean a lot!

engifineer

An oversize exhaust is known to cause loss of performance in most cars. Gasses are allowed to cool more while in the system due to the lower velocity (makes it harder to move). The lower velocity also affects the scavenging that a properly sized exhaust offers. Even with significant boost, 2.5" is probably the largest exhaust you will ever need with it. Bigger is not better with exhaust.

I wont even go into the pulleys, there are enough arguments on here about that.

As far as "gains". I could care less what you see on a dyno. I have seen dyno numbers advertised for parts that did not equate to any real performance gain.. so the numbers meant squat. Show me consistent increase on a track and I will believe it.

No offense at all intended towards you. But ask any good, knowledgeable custom exhaust person and you will most likely get the same answer I just gave you. Some will argue that "well, I ran open headers, and did well, so bigger is better", which I will follow with "First, you probably did not do better on this car with open headers.. second, huge exhaust in no way simulates open headers. The gasses are still in the system regardless of exhaust size"

MIAPLAYA

I have yet to see a turbo 2.0L or higher car lose power with a 3" exhaust. Sure on an N/A car going to large will result in a power drop. But a turbo car has a different set of needs. The number one need is the least amount of backpressure possible. Reducing the back pressure increases the turbines efficiency. Since the scavenging of exhaust gases from the cylinders is happening before the turbine wheel running a larger exhaust should have no bearing on this.

kungpaosamuraiii

That's true but you know that the exhaust cools down at the rate at which its volume increases. Of course, cool gas equates more back pressure since it's more difficult to move.

But of course that's all academic. I may as well wait and see what others get with the tC.

jam0321

you have received a lot or respect from people on this forum for your technical knowledge and I don't take any offense from your opinions but I did exactly what you wanted and asked a few "knowledgeable custom exhaust persons" and here is what they said.

Garret, tech advisor for HKS "based on our work with the Nitto Scion tC, we were able to graph the gains and loses from different exhaust piping and systems. It shows here (looking at his flow chart) that with the 2.4l size engine, anything above 300hp would ideally have a 3" system. Bottom end would suffer slightly vs the 2.5" but your flow wouldn't be inhibited at the top of your power band as it would with the 2.5. I would recommend the 3" IF you are going 300whp and above. The 2.5 is just going to be maxed soon there after"

Charles, sales staff for Greddy "our shop car is running a 2 3/8" cat back because we are keeping the exhaust street legal and we didn't find a need to go any bigger unless we were going to push 300whp and beyond."

And of course our guy who is building the system completely agrees with the above statements. He is also one of the top Subaru and BMW custom exhaust manufactures in the states but he is bias since it is his system.

Anyway, the trend here sounds like anyone and everyone who builds, creates, and develops exhaust systems agree that a 3" is sound for 300whp and above. So if you are not going that high then by all means, get a 2.5" system. Dezod's looks great.
If you are going to make more then you need more...

As far as the pulleys, there are some still availble so contact Greg before they are all gone. $100 shipped is darn good!