What is the difference between HFPCs and PCDs?
Confusing Name Guy
Joined: Dec 2014
Posts: 1,729
Likes: 299
From: Toronto, Canada
High flow pre-cats are essentially better flowing catalytic converters, so you won't have to deal with most of the issues inherent to deleting your cats, such as the strong smell and pronounced rasp of a catless exhaust.
Pre-cat deletes on the other hand are exactly what the name implies - they delete the 2 primary catalytic converters, so you're effectively catless.
Neither option should throw a CEL, as the HFPC are still read by the car as cats, and the PCDs use a defouler to trick the ECU, but the PCDs are definitely more likely to cause issues in this case.
There's also a slight power difference between the two - most people have seen a loss of a few (we're talking 2 - 3) whp going from PCD to HFPC.
At this point you want to decide whether you're OK with the smell / rasp of PCDs, or whether the HFPCs are more to your liking albeit at a higher price point. Also keep in mind that if you need to do emissions testing, HFPC are much more likely (at least from what I've read) than PCD to pass.
Pre-cat deletes on the other hand are exactly what the name implies - they delete the 2 primary catalytic converters, so you're effectively catless.
Neither option should throw a CEL, as the HFPC are still read by the car as cats, and the PCDs use a defouler to trick the ECU, but the PCDs are definitely more likely to cause issues in this case.
There's also a slight power difference between the two - most people have seen a loss of a few (we're talking 2 - 3) whp going from PCD to HFPC.
At this point you want to decide whether you're OK with the smell / rasp of PCDs, or whether the HFPCs are more to your liking albeit at a higher price point. Also keep in mind that if you need to do emissions testing, HFPC are much more likely (at least from what I've read) than PCD to pass.
Former Sponsor
Joined: Nov 2005
Posts: 1,697
Likes: 492
From: Chicagoland
Thanks for the help guys. 
Here is a quick RV6 crash course, this is rough draft that will eventually be added to the webpage. You can get more details on the rv6 website Welcome to RV6 Performance
The order of exhaust components.
Heads (engine) > precats > Jpipe > 3rd cat > exhaust
Jpipe+3rd cat delete
The RV6 V3 jpipe is our latest design and has the best gains due to its 2.25" long runner design. It replaces both the factory jpipe and 3rd cat in one piece. No check engine lights are triggered since there are no sensors on the 3rd cat. It is recommended that you get the jpipe before PCDs or HFPCs.
Pros:
Good mid and high range gains
Replaces factory jpipe and 3rd cat in open piece
Bolts up no modifications needed
No obvious place for a 3rd cat.
Cons:
May not pass visual inspection in some states.
Precats
There are current 2 RV6 options for a precat replacement. These options are effective because Honda used a very restrictive precat design. They are made with stamped sheet metal to reduce cost and have a small 1.75" out.
PCDs or (Precat deletes) replace the factory precats with a straight pipe using smooth flowing castings a 2.25” outlet. Precat deletes include special adapters for the O2 sensors and do not throw a check engine light.
Pros:
Maximum performance gains
Low cost compared HFPCs
Cons:
Raspy exhaust
Exhaust smell
May not pass visual inspection
Requires an extra resonator for rasp free operation
HFPCs or (High flow precats) replaces the factory precats with high flow catalytic converters. They offer the best of compromise between performance and daily drivability. They are also paired with our smooth flowing castings 2.25” castings.
Pros:
No rasp
No exhaust smell
May pass visual inspection
Cons:
More expensive then PCDs
Slightly less power gains compared to PCDs
The order of exhaust components.
Heads (engine) > precats > Jpipe > 3rd cat > exhaust
Jpipe+3rd cat delete
The RV6 V3 jpipe is our latest design and has the best gains due to its 2.25" long runner design. It replaces both the factory jpipe and 3rd cat in one piece. No check engine lights are triggered since there are no sensors on the 3rd cat. It is recommended that you get the jpipe before PCDs or HFPCs.
Pros:
Good mid and high range gains
Replaces factory jpipe and 3rd cat in open piece
Bolts up no modifications needed
No obvious place for a 3rd cat.
Cons:
May not pass visual inspection in some states.
Precats
There are current 2 RV6 options for a precat replacement. These options are effective because Honda used a very restrictive precat design. They are made with stamped sheet metal to reduce cost and have a small 1.75" out.
PCDs or (Precat deletes) replace the factory precats with a straight pipe using smooth flowing castings a 2.25” outlet. Precat deletes include special adapters for the O2 sensors and do not throw a check engine light.
Pros:
Maximum performance gains
Low cost compared HFPCs
Cons:
Raspy exhaust
Exhaust smell
May not pass visual inspection
Requires an extra resonator for rasp free operation
HFPCs or (High flow precats) replaces the factory precats with high flow catalytic converters. They offer the best of compromise between performance and daily drivability. They are also paired with our smooth flowing castings 2.25” castings.
Pros:
No rasp
No exhaust smell
May pass visual inspection
Cons:
More expensive then PCDs
Slightly less power gains compared to PCDs
Last edited by Richie v6; Mar 31, 2015 at 05:27 PM.
Thread Starter
Intermediate
Joined: Oct 2014
Posts: 49
Likes: 4
From: Seattle washington
[RV6 V3] Pretty much HFPC is a piece of equipment that provides better flowing catalytic converters you said.....
Will there be a noticeable power/sound once HFPC is installed ?
Another words, does really worth investing $570 + shipping for merely better catalytic converter..?
Will there be a noticeable power/sound once HFPC is installed ?
Another words, does really worth investing $570 + shipping for merely better catalytic converter..?
Three Wheelin'
Joined: Oct 2012
Posts: 1,853
Likes: 603
From: South Florida
Former Sponsor
Joined: May 2010
Posts: 2,228
Likes: 354
From: Branford, CT
^ FamilyGuy is right. Freeing up catalytic converter flow is one of the best ways to gain horsepower from these cars. A catless J-Pipe helps a lot too. Our V2 J-Pipe is a big power adder too and can help gain you some horsepower and torque.
XLR8 J-Pipe - Excelerate Performance - Japanese and European Performance Specialists!!
XLR8 J-Pipe - Excelerate Performance - Japanese and European Performance Specialists!!
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I've got rv6 v3 PCD+jpipe, MM delete & stock other exhaust wise. Rasp is only there heavier throttle & starts bout 3k RPMs. Smell is there, but get use to. I've grown to like the sound personally
I also keep a high flow third with PCDs. Not for the smell, but it was always better having at least some kind of cat, even if its high flow. Keep in mind high flows are great for emissions states…or states that do visual checks.
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