I'm looking to replace my stock Cat with an HFC, but also trying to keep the noise increase at a minimum. I'm also planning on swapping out my turbo to the CBRD BBX Lite soon.

I noticed the UR ceramic HFC is good for up to 450HP. Seeing that our RA can barely get up to 350HP after an evox turbo swap, shouldn't this be good enough for almost everyone? Or is the metal HFC just better overall?

how much better is the UR ceramic HFC compared to the stock cat?

 

Keep stock cat or go Milspec 100 cell

 

I bought the downpipe and HFC from here:

http://www.deporacing.us/APT-Products.html

for when I do my Evo X turbo swap, although my may put on the HFC sooner.

Prices are very reasonable, and the quality of the prodct I got seems very good. I also purchased their LICP and UICP for my Evo X intercooler swap - these are already on the car.

 

how's the noise level compared to stock? and will this pass emission? I don't want to keep swapping out cats when its time for inspection.

 

^ +1. Also, @Razorlab, what made you recommend the Milspec 100 Cell product over all the other HFC's on the market?

 

Theres hard data somewhere on these forums on the flow between stock cat, ceramic high flow, metal high flow, and test pipe. Try to find it.

I personally have the UR metallic HFC. I wanted the ceramic because it looks close to stock and it is sufficient up to 450hp, and I heard it wasn't much louder than stock. But I got an awesome deal on a used metallic HFC so I went with it.

I can't comment on the noise increase just from the cat replacement because I upgraded from a catback to a full exhaust at once, but going from a catback to a full exhaust, there was a noticeable increase in volume of the exhaust

 

1 million percent this. (Unless, of course you'd like to reconsider a test pipe)

Milspec 100 cell is just that, 100 cells (openings in the catalyst honeycomb) for the exhaust to pass through, most other HFC's are using 300+ cell internal catalyst designs. That means that the 300 cells in the same area as a 100 cell cat are required to be 1/3 smaller and are essentially more restrictive due to size reduction and more physical catalyst material surface area; not to mention that there are plenty of aftermarket companies out there using cheap materials that will degrade quickly over time. The Milspec 100 cell has been proven to be nearly identical to test-pipe flow and build quality is top-notch.