Got a quick question for the exhaust experts. I was talking to a local shop here in town and asking about having a custom exhaust built. As we lifted my car onto the hoist the mechanic started to explain a few things to me and to be honest I left a little disapointed. So if anyone here can clear a few things up I would appreciate it.

Heres the story....
Basically he said because our engines/exhausts are tuned we have an o2 sensor before and after the cat. This means that those sensor are monitoring the exhaust leaving the car. If for some reason there is a change then the o2 sensor tells the ECU and readjusts the air/fuel mixture. He said the best thing (power wise) would be to start just after the header and build a full one-piece system all the way back (removing the cat), but to do that I would need o2 omitters so the ECU wouldn't change the mixture. He said doing anything else really isn't worth it cause the gains compared to the cash being spent wouldn't justify it.

Now my question is.... Is he right? And where can I find o2 omitters/simulators for the RA. ORRRRRRRRRRR is this whole thing useless all together, because freeing up that exhaust will just create less back pressure resulting in a whole lotta less torque?

Coles notes... I heard a lot of things, don't know if there true, want a custom exhaust, is it worth it?

 

as for simulators is concern for the ralliart casper electronics is working it.. i bought it (part 104059) and cant plug it, i reported it and got the answer of the plugs mis match the wire's plug they are working on it for proper fitment.....
anti foulers havent worked for me so that is my pov


as for a custom job depends on the components and the bends.. i had a 2.5 custom job with an aerospeed muffler it sounded cool deep and nice.. butt dyno felt good but the real dyno reported a deficit of 15hp so beware what you are doing.. as far as exahust theres no better thing than stock imho
the rrm axle back nice,shiny and sounds deep but didnt worked for me also... lost hp and tq so i sold it...

hope this helps

 

You can simply have them weld the bungs for the O2 sensors right back into the new pipe. I havent examined my RA in minute detail, like I have the Mirage, but stock for stock, I dont think it is any restrictive in the exhaust. I could be wrong but it seems pretty tuned stock (in terms of manifold design and exhaust) to see any real comparable gains from upgrading either.

 

ya, u will throw a CEL if you drop either of the sensors. Going straight single pipe would be best, power wise, but its dumb. you cant ever take it off! make it in 3 sections. I also think a highflow cat is just as good as no cat. as for backpressure, dont worry about it. our car does fine /w a stock motor and 3" exhaust. my friend justin had that exact setup and pulled as well as any (actually, pulled better than it did before)

 

Thanks for all the quick responses guys...

That worries me!

You had a custom set-up didn't you? What were your gains with just the cat-back system?

 

I don't know if this is an issue for you or not, but if you do a complete one piece and omit the cat you will fail emmissions standards. I don't know if you guys get tested over there in Canada, but I know here in Ohio I would fail.

 

Yeah in Alberta they are not testing as of right now so I am not to worried (yet)

 

You would fail an equipment check, but you should be able to pass the sniffer test with proper tuning.

 

Ya, I dynoed before and after. ran the dyno at the same place, on the same dyno with the same guy doing all the work and running the car. The gains up high are visable and real and worth it if uve done other standard breathing stuff. from about 4000 RPM up, there were good gains in power, but better gains in torque. Torque ususally drops off realy fast after peak and it slowed down the decent pretty nicely. It also dropped my 1/4 time by about .2

but make sure you only get true mandrel bent piping and that they shop lays out a good flow for the piping with the lowest angles as possible. This can make or break a good exhaust.

Also, dont expect to slap this on a stock car and have it make any difference. Exhaust is a support mod for other mods. When you are making more power, you are making more exhaust. The amount of power is directly proportional to the air coming into the enigne, which is directly proportional to the air exiting the engine. duh =) the stock exhaust is perfect for the car in stock form, but if you are like me and are already seeing gains of about 25whp/25tq from other mods, a bit more exhaust bandwidth doenst hurt and will only help more in the future as you begin to work on other raw power mods.

 

i dont want to sound like im bashing you or your buddy but did he dynoed the car with a 3in setup or is it butt dyno?
a 2.5 made me los 15hp free flowing...

 

nah, he didnt dyno but we took it to the track. i frequent this track and it does suck (lane dips, vht isnt refreshed so its more slick than stick, timing system is usually broken or poorly calibrated). anyway, i usually get 15.2 - 15.3 at this track (wrxs get high 14 to low 15s most of the time.... the track REALLY is that bad. i was there last night and a buddy's wrx couldnt get outa the 15s!) he was hitting 15.4-15.5s all night /w 3" exhaust. that is wher he shoulda been compaired to me and the fact that I have a better air/fuel and motormounts. i have some videos of the runs posted on here somewhere

funny tho, last night they had to hand-write slips good thing the conditions were horrible caus i woulda had a best time and it was on a hand written slip, no one would buy it

 

found it:

https://www.evolutionm.net/forums/sh...hreadid=132459

 

Fifty, Why not look into the VRS Catback, they've been pretty good to everyone so far.

 

In the first post I stated I don't want just the cat-back I want the whole exhaust system done from just after the headers, back. No cat's. For the same price as me buying an aftermarket cat-back I can have the whole thing made custom and more.

 

now that track sucks if you have to get a han written slip.. and i tought my track was 'sucky' because of the facilities <-- hope i wrote that well

but still he should dyno.... never trust butt