02firehawkT/A

iTrader: (2)

Hey guys - I did a search on this but could't find an answer to my specific question. If this should be in the tuning section instead of external then my apologies, but it's a little bit of both.

My exhaust setup is as follows: LT Headers into a TSP 3" catted y-pipe, out to the stock Firehawk dual/dual catback. Rear O2 sensors have been deleted and tuned out.

My question is this: I recently bought (1) QTP low profile e-cutout that I plan on installing after the header and front O2 sensor but before the cat, probably on the drivers side. When open, will having (1) cutout as opposed to a cutout on both sides cause a tuning problem? One cylinder bank will have less exhaust restriction than the other, so I'm thinking it might? I'd rather not have (2) cutouts for noise and cost purposes but if it's going to cause a tune/engine issue I guess I don't have a choice. Basically what I'm asking is can I have a cutout on one side of the y-pipe before the merge without causing A/F ratio or other problems. Maybe I'm reading too much into it.

Edit: I guess I could just put the cutout in the I-pipe in the stock catback, but that wouldn't give me much if any gains at all. Any advice is appreciated, thanks in advance.

redtan

iTrader: (5)

A cutout before the O2 sensors is going to cause issues on that bank with those sensors and the car will run like crap. Even more so it will run like crap if it's only on one side of the engine but not the other. You really should be placing those at least a foot if not more after the O2 sensors if you plan on running around part throttle with them open. If you were opening those only at WOT then it wouldn't matter as the O2 sensors are not used then, but if you're going to be idling or cruising with those open near the sensors it's gonna give false readings and cause the engine to not run right.

Putting a single cutout in the I pipe is the best and what a lot of people do for this very reason. Also, the midpipes are not really where the restriction is, moreso in the single pipe after the Y merge. So ideally, that's where you'd want the cutout to go as to benefit you the most. If you put it too far down the I pipe yeah it's a waste as the restriction is present, but if you put it right after the Y merge it's going to work fine.

02firehawkT/A

iTrader: (2)

Thanks for the input. I'm looking to put the cutout in the Y-Pipe after the header and O2 sensor but before the merge; My exhaust is set up as follows as of right now:

Header (with O2 sensor inside) --> Y Pipe --> Cat (in the Y-pipe) --> I pipe/catback

I'm looking to do the following:

Header --> Y-pipe --> E-cutout --> Cat --> I pipe/catback

But only on the driver side. I realized that there won't be enough room on my Y pipe to put a cutout before the cat.

Would this setup work fine? Also, I meant to post this in the external engine section. Mods feel free to move. My apologies

thunderstruck507

iTrader: (18)

Either put the cutout in the I pipe after the merge of the Y, get one for each bank in the y pipe, or do not install a cutout at all.

Do not put a cutout on one bank of the y pipe before the merge and not the other.

redtan

iTrader: (5)

What's the point then? Half of the cylinders are still going to be restricted by the exhaust while the others are not.

Either put 2 on each pipe, or one after the merge.

That's like doing a head swap but only one head is being upgraded while the other remains stock...

02firehawkT/A

iTrader: (2)

The point was to bypass the cat on that side. I can't bypass the cat on the passenger side because the pass side cat on the TSP Y-pipe attaches right to the header and there's not enough room I would have bought (2) cutouts and done it that way if the y-pipe allowed for it.

I guess the cutout will be going in the I-pipe then. That's a bummer. I can't imagine I'll be picking up much power by bypassing the dual/dual catback, apparently it flows really well

jimmyblue

iTrader: (11)

I found that with my spark asdanced as much as the
closed-cutout WOT operation would take, I got a lot
of ping with the cutout open. Which means it's doing
the job, but you need to leave some timing on the
table for the open case.

Since you only have one timing table, one airflow and
one fuel command to share between banks, you want
those banks to be as identical as possible. A cutout on
one side will unbalance things. This could just be some
loss of power, or could be destructive (see ping).

You could put the cutout in the I-pipe.

With my CME and shorties there is enough back pressure
in the system at WOT, to blow an O2 sensor out of the
hole (weak threads, but still). Something to be gained
with a cutout, even if it only rolls on above 5000RPM.
Catback is about the same as D/D.

jlcustomz

I made one manual operated cutout right after one side of my x-pipe , which basically make it function as a y when the valve is open. I also oval shaped a larger pipe size connecting to the exhaust for the valve to give it more flow area. Cutout is in the old u-tube video on my link.
As far as only having one large valve, remember that some of the gases can still flow through the rest of the exhaust at the same time.

02firehawkT/A

iTrader: (2)

Thanks for the input guys. With a D/D catback, does anyone think it's worth it (power wise) to put the cutout in the I-pipe? I'm leaning towards not putting it on and returning it because why deal with cutting up a discontinued exhaust and having potential exhaust leaks for only a few HP gain?

If there's a good gain to be had by bypassing the D/D catback, I'll definitely have it installed. But if there's not I'd rather save the $500 between parts and install and use that $500 somewhere else on the car

redtan

iTrader: (5)

As always, cutouts are more for sound or those seeking to extract every last hp out of radical setups where even a dual 2.5" catback is a restriction. So people with big engines, big turbos etc. will see good gains for the money.

You however will not see as much (especially so far down the exhaust) for it to really merit that much money. The money could be better spent in other mods that will net you a better return. Putting that money towards a cam swap, gears, stall etc. will get you more of a performance increase than the few hp of a cutout at your power levels.