BXC2k

soz if this has been answered before... but I am thinking of getting either a test pipe or a HFC
but I cant really decide atm?

I'm running stock exhaust with the uk mod

I'm contemplating either to get a berk or a invidia

but can someone tell me the cons and pros of a HFC and a test pipe?

I heard over time test pipe can cause more problems to the engine?

chubbys2k

If your state does emissions or you care about the environment, dont get the test pipe. The difference in power from a hfc and tp is minimal from what everyone says.
I dont believe theres any problems running a tp other then a smell and burns a little more oil (also from what others say on here). I personally run a tp bc its cheaper then a real hfc and im a cheap guy. With your mods, i would just run a 63.5mm tp, no need for a 70mm on a stock exhaust until you have a real exhaust

Forziii

I'm assuming you'll need a HFC if you're in Australia like me. (test pipes aren't legal - if you care about that)
I'd go for a 70mm HFC if you're considering an upgrade to the exhaust later on down the track.

pros of a HFC: legal, less restriction
cons of a HFC: slightly more restrictive than a test pipe

pros of a test pipe: no restriction
cons of a HFC: illegal, harmful to the environment

IMO, the HFC pros/cons outweigh the test pipe.

BXC2k

Thanks!!

Guess... i'll do alittle more saving and hopefully get a HFC soon (Y)

B serious

Does either make a big enough difference from stock to even be worth it?

Depending on your model year, a HFC can also set a CEL.

The advantage of a test pipe is that there's nothing to break on the inside, weight (lol), cost, and flow. The huge disadvantage is the smell that will permeate into your shirt/soul. The environmental impact is considerable as well.

As a former TP user, I would likely go HFC rather than TP as well. But...how much of a difference does it make with a stock exhaust? Im asking because I don't know, BTW.

A comptech/CTE intake looks good, doesn't sound stupid like open cone intakes do, and probably makes more power than a TP/HFC. No?

Car Analogy

The only real advantage of a tp or hfc for this already extreme performance engineered car is to allow lowering wot vtec rpm. Something that actually would reduce hp of you tried it with the stock cat.

But you'd need an '06 or newer S that supports flashpro to do this easily. If you arent lowering vtec rpm, dont bother wasting your $ on a tp or hfc.

When Honda make the F22, the larger stroke required lowering redline. That meant narrowing the vtec powerband. Im sure Honda would have liked to have lowered vtec rpm to compensate, but ot turns out harmonics in the exhaust, due to cat, precluded this. So instead they did less desireable things like use a heavier flywheel so rpms dont drop as much between shifts, allow stay in vtec between shifts, etc.

A guy on this forum named Gernby endlessly experimented and discovered these harmonics, and how to get around them, and allow lowering vtec rpm. The single best engine performance improvement you can make on the S. He even designed his own cat, and his own exhaust system with his cat design, that takes most advantage of these harmonics. But you can still get a lot of the advantages with just a hfc (or tp), and flashpro to lower vtec.

Important, match diameter of hfc (or tp), to size of exhaust. You will lose power of you pair a 70mm hfc or tp with a stock or similarly sized (63mm etc) exhaust.

The stock cat actually flows very well. If you arent gonna lower vtec rpm, hfc or tp will not produce any sizable gains.

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