Hi to evrebody.

I need your help in order to understand the different in terms of performance between theese 2 modification.

I have the Apexì power intake, HKS evc ez2 boost controller and Blitz Nur spec R cat-back.

I will put on the front pipe ( knight sports dual tube) and the midpipe or hi flow cat, the ECU will be made from Knightsports.

Questions: What will be better??? midpipe or hiflow cat???

Consider that i use the car also in the city and i like power also at low rpm e not just above 4500rpm.

Will i feel the difference between the stock cat and the hi flow cat???? how many Hp you think that make the difference??

What you can tell me with your experience??
What is the right choose for me???
If you have any number or dyno test with and without the cat in the same modification please send me by e-mail. Thanks

 

Most restrictive to least restricitve:
1. Stock cat

2. High-flow cat = Good power gains, clean smelling exhaust. You will feel the difference between a HF-cat and the stock cat. You will also save 20 lbs. too. The HF cat only weight 12 lbs. vs 30+ lbs for the stocker.
3. Resonated Mid-pipe = Better power gains & quiet but smelly exhaust. It's a trade off.
4. Mid-pipe = Most power gains, but loud as hell!

I've had them all and I am currently running the RX-7 Store Resonated Mid-pipe. I love the added power and responsiveness. Don't like the smell. Like I said earlier, "it's a trade off."

You need to figure out if you want to deal with the smelly exhaust and lack of emissions. If you decisde to with a Mid-pipe, resonated or otherwise, you may be required to add fuel(new ECU, remember:Three flow mods=Need new ECU), or port your wastegate(to avoid boost creep, maybe)

 

i have a full exhaust with no cats... it has a nice idle, but gets quite loud WOT.

 

i agree

 

don't forget the bumper area near the exh. gets a yellowish tint to it after a while with a midpipe. easy to clean with 409 or something, but still, so you know...

 

Hes got it here, the more performance you want the less streetable its going to be (trade offs)...I have a regular mp(non resonated) and it is loud and smelly, but I deal with it. Also you have to worry about boost creep with mp's unless you port your wastegate. So for your application a high flow cat would probably be the best choice, but thats just my opinion..
Kyle

 

midpipe really isn't THAT loud. I mean these guys with their V8s are louder IMO then my car with midpipe.

Just WATCH the boost level.. creeping WILL MOST likely happen if you run full exhaust with no restrictions

 

See "midpipe questions" thread. The "super high flow" cat seems to flow just as well as the midpipe but is quieter and no smell (and no "smoot" on the bumper cover .

 

I have a strait midpipe sitting in my garage and i've been meening to ask about this. Thanks for the post pietrino.

 

There are two issues with the midpipe. You won't pass clean air tests and I don't know if you have them or not in Italy.

Second, as they said above, you will get a lot more boost than you do now and you better be tuned for it or else kiss the engine goodby. This is a particular problem if you are running sequential twins. Nonsequential guys report far fewer overboost problems.

High flow cat is probably the best choice for a daily driver. It does restrict boost but that can be a good thing. Around town I make a rock steady 12 lbs and at the strip with 103 octane race gas, I get 17-18, never more.

 

i will take the Hi Flow cat.
Thanks to evrebody!!!!!!
:-)

 

tcb100 made a good point on how the high flow cat restricts boost a little. I'm currently running a high flow cat, but when i buy a PFC and boost controller within the next month, i'll be getting a midpipe too, and run that when i feel like i need that extra bit of power.

Gives the best of both worlds.

 

i run midpipe for the past week or so and my boost stays at 10-11 PSI all the way to redline.. my mods are


1.Power FC
2.DP,MP,CB
3.Racing beat cold air duct
4.K&N filter

thats it, stock IC and airbox still