Cat delete gains

[MA70-3.0GT]

+1 on the direction this thread has taken!

The vectra has a butcher's shop special system on it (Irmscher back box and a bunch of 2 1/4" tube tacked loosely together, and no cat which is 'naughty' for a 2000 registered car) which actually sounds quite good thrashing round the back lanes, bit like a WRC super 1600 car on steroids!

[Ranma]

MA70-3.0GT, at least you have the wheel on the right side of your Supra. Am thinking about returning to Japan but my Supra has it on the left side
Anyhow to bring her back to Japan will need a CAT among other things. The Supras are becoming rare in Japan.
Oh I want mine to be as quiet as possible but without losing power.

[gordyordy]

My supra is a 87 7mge non turbo...I live in oly washington so I'm not worried about emission problems. I want to delete my cat...where do I find a tube to replace it? Should I install it myself? How much would it be if I had the shop install it?

[907mge]

On your 7mge without a cat you may actually lose some power since the main gains are on the 7mgte that is turbo and does not need backpressure like a 7mge does.

[CanadianBak'inSupra]

used to have headers and full 3 inch on my 7mge with no cat.

sounded sexy, and with the headers i felt a good difference...
if your not going for many other AM parts slightly smaller woulnt not hurt maby a 2.5 or 2&3/4 would be perfect

[cre]

No 7M-GE sounds sexy with that kind of setup.... sounds more like a Civic with straight pipe after getting fisted.

[CanadianBak'inSupra]

no a civic will have a 1&3/4 inch to a 4 inch muffler haha

[gordyordy]

what if i just put headers on it? would it sound as sexy?

[907mge]

I don't think the sound changes that much with the header atleast not for me. The problem is that there are only 2 headers made for the 7mge and they are basically the same just made from different materials. Pacesetter and obx are the 2 and they are so so. Both will have to be modified to fit, o2 sensor moved and either wraped or ceramic coated to reduce under hood temps.

[cre]

Turbo, resonator, cat, muffler.... in that order are what affect the sound the most. Pipe diameter affects both pitch and volume but isn't something you should screw with much if you're worried about performance and you car is mostly stock (and there's not a single upgrade you can make on a GE to justify larger than 2.5", turbo'd engines are a whole different ball game).

Turbos, cats, resonators and mufflers all smooth out the oscillations in your cars exhaust. The exhaust exits the header as a continuous series of little bubbles. The pockets of lower pressure and then the jump back up are what cause that wicked lovely ricer fart sound... there's no performance there, just someone with no clue how it works or is looking to be loud and obvious for the cops just for the sake of it.

Now there are different and better types muffler and resonator... the stock cat flows VERY well, but you can get even better flowing ones pretty cheap. As for mufflers and resonators you want to look for free flowing but from a company with a clue... I like Borla's ProXS series and Magnaflow, but I find I prefer the sound of the Borla most. Both are straight through mufflers, to level the tone more and reduce at idle and low load volume a dual outlet model is preferred. With resonators you'll be hard pressed to find a straight through model. There is one made by AeroTurbo which is a straight through, helmholtz resonator... the only way to go. Smooth deep sound with an increase in exhaust velocity.

One more thing you can do to help the exhaust system is to increase the pipe size after the resonator by about 1/4" this provides extra volume to allow for the increasing density of the cooling exhaust gasses.... but don't jump up in size too quickly. The ideal pipe diameter is actually a very small and steady increase in size... a VERY long narrow cone. Kind of hard to get that fabricated, but you can use a couple small steps up in size as the pipe gets closer toward the back of the car.

No headers have very little affect on sound.... at least on a car with such a long exhaust track, any interruptions and piping anywhere near the stock diameter. Don't buy headers for sound.... don't buy any upgrade just for sound, it's a waste of money, IMO.