hey, i was planning on doing some stuff to the exhaust of my car this summer, but began thinking... my original plan was to have a sleeper car... stock hood, wheels, etc. well, since an exhaust can be a big give-away as to what you're running, would it make sense to get some LTs, high flow cats, and cutouts instead of the cat-back system i was originally planning on? i know it will cost more, but it should perform better i would imagine. would the stock y-pipe restrict it too much? do they make aftermarket street legal y pipes?

edit: also, i forgot to mention, i was referring to electric cutouts. if i were to come to a stop light and find i could get into a race, would it take time for the engine computer to realize it's got to tune itself differently when the cutouts are turned open? or is it like instant?

 

Here's how I would do it.

Long tubes.
Custom y-pipe with dual cats.
Cut-out.
If your car has dual exits, convert it to a single exit.

 

eh, it would get a bit costly. here are the prices i figure for everything:

coated hooker headers - $630

random tech y pipe + 2 cats - $570

single QTP cutout - $155


im not even sure what the measures of all the piping is, i need to figure out what the diameter of everything is before i buy it so i dont have a bunch of crap that doesn't fit.

 

i could probably get away with saving for the y pipe, cats, and cutout by the end of the summer. i may need to get a CAI at a later time. for the most part im looking for sound first, but it's got to look stock and perform great.

i may just run stock everything and get cutouts and a CAI. i heard a clip of it when i searched for info on this topic, sounded pretty nice.

 

There's nothing for the PCM "to realize it's got to tune itself differently".... Opening the cutout(s) improves the exhaust efficiency, which improves the engine's volumetric efficiency. The engine flows more air, the MAF sensor measures the extra air and the PCM adds fuel at the correct ratio to match the extra air. No "learning" involved.

Of course all this assumes you have an MAF sensor, but since you don't include any info about the year of your car, its just a guess.

 

I have Hooker LT's, no catalytic converter, Dynomax Turbo muffler. Can barely hear the car.

 

oops, i forgot to put my new image in my sig...

well its a 1994 Z28. so yes it has MAF. i want a mean sounding exhaust, but only when i want it to be. i think cutouts will be my best option. i think ill get the cutouts and a CAI for now, and ill give myself some time to think about what next to get.

 

What about if I don't have a MAF? It needs to relearn?

 

Sorry, it's for my 1993 Z28. I'll change my sig.

 

That's what differentiates a speed-density car from an MAF car. The MAF measures the air mass flow directly. The speed-density setup calculates air mass flow from the RPM, displacement, volumetric efficiency (VE), inlet air temp and manifold absolute pressure.

Make a change that alters volumetric efficiency, and you need to tweek the VE tables. Its not likely that simply going to a cutout would upset things enough to worry about, but add together a few changes that improve VE and you need to "tune".

Its not a matter of "learning".... you don't see the effects of VE changes at low load/closed loop operation. You see the effects of better breathing at WOT, and in that mode, learning is not enabled. Its stuck with whatever it learned in closed loop.

 

so would i see noticable gains from a cutout and moroso CAI?

 

Your in the 757 I understand completely... nothing more annoying than some hardass 757 cop that hates modified cars.

Run what ever you want just get a quiet muffler. I reccomend flow master, but there's others out there. But a Sleeper Camaro doesn't require much effort consider a majority of people only add on some ZR-1s and call it a day. Not very hard to beat.

 

yeah, thats partly the reason, ill just open up the cutout whenever i am away from cops/want to set off car alarms/need to scare little kids out of the street so the little turds dont run in front of my car and hit it with a freaking tennis ball...

i actually plan on not buying a cat-back... since the cutout is so much more trick and it bypasses in completely when i need it to perform. ill probably get the cutout for some nicer sound and save up for headers/maybe y pipe when i have the money. its gotta make the ladies at school turn their head and think "hey whos driving the badass car... hey its a camaro. he must be cool" next school year

 

If you are taking the cats out I would replace them with bullet race mufflers if you want a "sleeper" exhaust.... cats help out a ton in noise reduction and without them you could have some annoying drones in the cockpit.

Bret

 

I would imagine that "sleeper" and "quiet" go hand in hand. Another
blow it for a sleeper is long tubes. I would keep it as inconspicuous
as possible, go with 2.5" mandrel bent pipe for duals or 3.5" for a
single and a really quiet muffler(s) like ultraflow or magnaflow. If
your system is clean, the cutout won't get you much, which is also
a blow it.