John@Fabspeed

There is a different tune as well to the optimize the setup with the catted Sport Headers versus the catless Race Headers.

It is no secret that strong engines (such as the 3.8L) make significantly more top end power when you run catless, while the low/mid range remains similar.

This is a bit of an odd analogy i'll admit...but think of it like you've been exhaling through a sponge all your life. All of a sudden that sponge is replaced by a strainer and you can breathe through it Much better, but still can't blow through it as hard as you can. Then the strainer is taken away and you are free to maximize your ability to exhale. Essentially this is factory vs high flow cats vs catless headers, and the more potential the engine has the bigger the performance gains are going to be between those three stages.

If you are looking for the most horsepower and top end performance out of the GT4, a full catless GT450 race package is undoubtedly the top option.

Dr. G

I agree that loud is good - and yet it was still recommended I go with the sport headers if running primarily on the street.

Fabspeed has a set of spacers with mini cats that can be used with the race headers that apparently help with CEL issues when going back to a stock tune.

http://www.fabspeed.com/universal-o2...ic-converters/

QuickOne

What's the vacuum canister for? I thought that was an air/oil separator originally.

realdrray

It's to better maintain pressure to operate the valves more efficiently

BBiAutosport

RealdRRay & John@Fabspeed,

The car looks stunning and thank you for sharing!!! You guys have been great to work with and we are proud to have you guys as a partner back East!!!

- Jerry@BBiAutosport.com

QuickOne

The valves in the exhaust?

I honestly would like to get rid of those and just have a basic exhaust. I don't care if it's loud all the time - that's the first thing I do when I get in the car is his the sport button.

John@Fabspeed

That's exactly right Ray

Our pleasure Jerry! You guys make a fantastic product, and one we would love to install again! If you have any guys out here be sure to send them my way, i'll be sure to take of them

That's correct. The factory vacuum system does not retain enough vacuum pressure to keep the valves closed if you turn off the car for a short period of time, so startup will always be quite loud before the pressure builds. Also, when idling valves can sometimes flutter slightly if the pressure becomes insufficient. With our vacuum canister installed it provides a vacuum reservoir that maintains pressure to the valves so there is a longer period of time where you can restart the car with valves closed instead of building up pressure again. It also helps provide sufficient pressure to the valves in idling conditions to reduce valve noise.

To note...we did customize one of them to make an air/oil separator for our 930 turbo

Loud with PSE activated and Loud with our Valvetronic Exhaust System in open mode are two different animals. In providing a great deal more power it is quite unrestrictive, making it much more aggressive with greatly enhanced burble/overrun with a true Cup Car sound. "What's wrong with that?!" As we all know, an unrestricted exhaust also has a stronger tendency to penetrate the cabin of the Boxster/Cayman in high gear at cruising speed between 2-3k rpm. Therefore, most people would prefer an option to "tone it down" at a push of a button for better comfort on the highway and around town...then WILD when passing the dreaded Prius in a gap on the backroads.

If indeed you'd like a valveless system, we do have a 981 Maxflo and Supercup system that will fit on the Cayman GT4 or Boxster Spyder and perform better than the factory PSE. However, they won't provide the performance gains of the Valvetronic Exhaust System that was optimized for the 3.8L,

digitalrurouni

So is the tune that's provided as part of these packages the 'stock' Cobb tune or do you guys do additional work on top of it?

trebien

I agree... I would have assumed 20 HP or so at the top, max...

John - maybe I missed it, but in order to better consider catted vs catless options and tradeoffs with sound... could you please provide a dyno of stock vs street420 vs catless450 packages?

Thanks.

John@Fabspeed

We do additional work on top of it as the GT420 package comes with one of our custom Protunes, as does our GT450 package.

It all depends on the engine, but this 3.8L responds exceptionally well to our catless Race Headers and does not like restrictions in the system. We were actually all shocked the GT4 was capable of 400whp in the first place. We would have thought the GT420 package would be our catless Race Header package, but this engine had so much more untapped potential than we expected. Here is a graph of the GT420 package versus our GT450 Package.

Jimmy-D

Greta numbers. This car must sound great and pull nicely.

It would be great to see its 1/4 mile times

digitalrurouni

Thanks for the reply and the dyno graphs! I would love to go with the catless setup but dang EPA

Dr. G

I'm ok with the EPA part of it, it's my ears and neighbors I worry about with a catless setup on the Spyder for primarily street use. I'm doing the GT420. Who knows, I may eventually trade out the sport headers for the race headers...

...but it kills me to pay more for less power by going with the cats

kahane18

Thanks John
See you tomorrow at the racetrack!!

digitalrurouni

Yep that is more of a