I've been searching through this thread and I found conflicting things on the HPS intake versus the PRM.

I suppose one thing I'd like to know (and I'm waiting for an email back from HPS about the same thing):

Does the HPS have a velocity stack in the kit? If not, is the inlet a 2" or 3" to have a velocity stack added to it with a different filter? I understand the PRM filter IS the velocity stack from what they claim.

I'm on the fence between the two. If the HPS can accommodate a velocity stack, I'll probably opt for it versus a PRM. Just want to double check before I pull the trigger.

 

Well the HPS (which i have) uses a K&N intake. So ask K&N if you dont from them for better answer.

 

Judging by the dimensions being a 2.5" inlet on their filter, I'm guessing the filter has some sort of rubber inside that makes a "velocity stack."

But, for it being cheaper than a PRM, it's easy to find a 2.5" - 6" velocity stack and use something like an AEM Dry filter. The big question is if the HPS MAF tubing is truly 2.5" on the end.

 

I am looking to replace the K&N filter on my HPS intake for GE8 Fit. The HPS intake needs a velocity stack as the HPS intake does not Vtec Kick anywhere close to as hard as the PRM intake (owned both). The reason why, as near as I can tell, is the K&N filter does not flow air fast enough to take max. advantage of the Vtec (PRM did flow enough to take full advantage but it will cause deafness it is so loud). So I too am looking for a filter that can take a velocity stack in that tiny space where the filter resides. Have not been successful. Have come up with a custom designed air filter. Now just got to get it made..
https://sites.google.com/site/drcust...rfilterforcar/

 

Then I'll try Takeda intake filter. I wonder if K&N intake's filters have velocity stacks where filters for competitors do nor. I'd think the company would say what they want in their filter.

 

The gains are negligible between the HPS and PRM intakes. The both suck in hot air. The advantage of a short ram intake is that it is easily accessible for maintenance. That's really it.

If there are gains to be made it is with a a CAI (like Injens or other equivalent). The CAI on this car is inconvenient to clean every ~15k miles; because it requires removing the bumper. That being said, the air filter doesn't need to be cleaned very often and it is not difficult to remove and install the GE8 bumper.

For reference I have the Injen CAI.

What are you trying to achieve? (race car, trackday, DD...)

 

I'm really just going with a short ram. I understand heatsoak issues with either intake. I currently have a cheapie heatshield on my DIY intake, but the reason I'm looking for a new intake is the plastic MAF tubing has warped and cracked.

Main thing I'm trying to achieve is just better efficiency overall. I have a small motorcycle aluminum velocity stack stuffed into my current filter, and I saw a difference in response with that.

As for filters having velocity stacks, the K&N is probably marketed like the Spectre filter I have with an "internal" velocity stack that is nothing more than the rubber grommet being shaped like a bellmouth. Probably the easiest thing to do is to look at the K&N filter part number, and find a filter that is 1-2" shorter. I also prefer dry filters as opposed to oiled.

I'm an A/T, so CAI isn't really an option.

 

The K&N Filter is an RU-2430, which has a height of 5 inches.

AEM 21-201BF is a round dry filter with a 6" flange ID with about .125" greater length... It could probably fit. No way of knowing just yet. Any filter with a 6" flange ID that's shorter should work.

EDIT: Correct K&N Filter for HPS is RC-9630. What was I thinking? Oops.