No I intentionally did not make that part of the kit for two reasons- it would likely cause issues trying to active the VVT pulley on 20V engines that still have them being used and second isn't that only bigports thing before the oil drains where introduced in the heads?

I would of been happy to answer this query, should you or anyone else have any product inquiries then feel free to send it to me directly. I don't want to leave my customers in the dark on how to do anything. As for what you want to know. This is a copy of the HKS kit and has the same instructions. ...

If you want to be exact then the opening is about 49.5mm, everyone just uses 50mm I.D stacks though.

What do you have in mind?

I can confirm that 90311-32020 is indeed correct

yoshimitsuspeed wrote:
When people say they want more torque what they mean is they want more low end HP. People just don't know how to use proper terminology.

Wow this is refreshing to read. Well done for understanding the concepts.

Most people say some 100mm or 110mm stack will give the best improvement over the complete range. Shorter will gain you power but loose torque. Simpelst mods you can do are intake, header and exhaust. this is incorrect, if you fit shorter than 70mm you loose power everywhere. Quite often going long...

Unless you're making a real high end engine then you will likely make more power with silvertop throttles