thinking of buying a high flow cat for my fd, but i dont want to play with the fuel ratios too much, it is bone stock right now and what i plan on only doing is a hks downpipe , k&n filter ( stock air box ) , ( stock cat-back) and a high flow cat if it doesnt mess with the air/fuel ratio too much. i want to keep the stock 10psi boost. but i would like to reach 240-250whp if i could with just those mods. is it worth putting in a high flow cat? how much power will the high flow cat add?

 

Put a downpipe and cat-back on. You will be making 240 rwhp or so. The K&N won't do much for you with a stock air box. A hi-flow cat should come after several other mods (or to replace a bad stock cat).

EDIT: the reason I say that is because a cat-back exhaust will make your car sound better (depending on what you get) and is a nice hp gain. You will gain about 10 rwhp with a hi-flow if you already have a downpipe and cat-back.

As long as you don't boost over 10 psi, your A/F ratios will be fine. You may need a boost controller if you do a complete exhaust with hi-flow cat to maintain 10 psi, especially in colder weather.

 

Agree with rynberg, just get a decent CB with the DP. The hi-flow cat may cause you to go over your self-imposed 10 psi limit, and you'll get more bang for the buck with those mods until you do more upgrades. Get a boost gauge, too.

 

aright you say the k&n wont do much, should i swich to an upgraded intake system? will make a big difference? also will i still maintain good a/f ratios.....

 

Yes, all three mods together will make a big difference, but I suggest you do some reading up on the various intake systems available, as you will open up a big can of worms if you ask "what intake should I get?".

If you do decide to get an intake, along with a DP and CB, there's a good chance you will go over 10 psi-- actually, the spiking will surely take you over 10 psi. Unless you control boost in some manner, you may be treading into dangerous a/f ratio territory.

 

i've heard hi-flow cats aren't worth it....might as well get a midpipe. something to do with the quality.

 

I've heard midpipes aren't worth it...might as well get a high-flow cat. Something to do with constant exhaust fumes, high noise levels, and boost creep....

 

I will sell you my K&N stock fit filter. I have the M2 intake in my FD so I do not need the K&N.

 

smg944,

I was in the same situation a few months ago. I decided to go with the catback and downpipe and reliability mods. Once I get a PFC I'll start modifying the intake and cat. As Kento said do research. I'm still doing it with regards to boost controllers and injectors and boost spikes and boost creeps and so forth and so forth. Make of list of the things you want to find out and search... I gaurantee it'll keep growing.

Victor

 

i take that to be sarcastic. what i meant was that the hi-flows on the market aren't that great, so the power gain "isn't worth it." midpipes have their bad point, but the power gain you get over stock compared to the hi-flows make them "worth it"

 

Had DP/Hi-flow cat/GReddy Sport Catback/K&N filter/RB intake duct/stock airbox/stock ECU/ported pre-control actuator pill for 10-psi boost control. Had no problems. Made 250 rwhp on the DynoJet with these mods. Hi-flow cat lasted 5 years and 74,000 miles. Now have a straight-through (non-resonated) midpipe with RB dual tip CB/GReddy 2-row FMIC/GReddy Airinx intake/Koyo rad/'99 J-spec twins/KDR large streetport/Power FC/1300-cc secondaries/NipponDenso comp fuel pump with Power FC tuned to 11 AFRs. Mustang Dyno rwhp is 306, estimated DynoJet rwhp is 360. Midpipe is stinky and loud (when you get on the go pedal). In return for putting up with the stink and noise, you get outstanding twin turbo and throttle response. The answer lies with you. What are you willing to pay, for more acceleration

 

K&N will be a noticeable improvement if you open up the air flow to the box. Either put on the RB inlet duct or do the stock box mod. You'll spike between 12-14 psi depending on the temperature. Hasn't been a problem for me in 3 years with the stock ecu. Don't have a high flow cat so I can't comment on that.