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True Dual Exhaust

new 3/1/03

Has anyone gone with true duals from the cats 1 & 2 back? What were your concerns and results? Thinking about this in 2 1/2 inch with Edelbrock RPMs. Would appreciate your thoughts and comments.

Llano Bill
99 SF

I think (not sure) that David D. did this about 3 years back. You might want to drop him a line.


True duals were tried on the V6 and with mixed results. The last reports were unless you had a full blown highly modded car, it wasn't worth it.

Even if you try it, 2.5" is WAY too big for even a pretty highly modded V8. I would think 2" would be more than big enough and a LOT easier to bend and route.

Edelbrock mufflers make lots of noise, but dyno testing has pretty much proven that for these cars a straight pipe in place of the muffler is not any better than a typical turbo muffler, and a Turbo has a lot deeper tone, is easier to mount and a lot cheaper. Same with Flowmaster box type mufflers. I tried several muffler combo's on my '89 and a cheap typical Turbo makes exactly the same HP as a Flowmaster or other expensive mufflers.

When you get into 500 hp then things start to change, but at the levels of most SHO's, you just don't need a straight through exhaust system. Some backpressure is good, especially for cars driven mostly on the street.

Don Mallinson

Thanks Rav,

I put a Borla cat-back system on the car. Not a true dual but pretty close. Troy Sours, June Han et al. did the same.

I cannot remember who it was that had a custom true dual straight pipe system installed, but he like the sound, but not the results.
Bill, unless you are going to run NOS or a bit of whoosh you're just going to spend money to lose speed. The car needs backpressure.

IMHO (Sorry Frank).


Sorry Jim,

I remember when the list first started up people trying things left, right and center. I even remember, I think it was Jim H. (though I'm probably wrong again) driving around with a thermometer under the bonnet to measure the differences under different conditions.

All the best,


Yes! It was Jim H. that had the true duals installed. He might have done some temp measurements also but I think Paul Nimz is the authority on that.

Since Troy keeps all the old messages from this list, maybe we could convince him to dig out the details. :-) Just kidding Troy.

(In full song) Memories!

P.S. What Rav calls a bonnet, we commonly call a hood. ;-)

I had 5 thermocouplers going to the engine compartment while going to the convention last year. :)

Paul Nimz
'97 TR SHO
'93 EG mtx SHO

Uncle Jim Peterson did this....he lives in Colorado. He went through a divorce and had to get rid of the Gen 3. It was red....

He had true duals and Gen 2 slicers on it when he sold it....

Kemp Beaty in Atlanta I believe bought it...didn't even realize it was Jim's old car when he went to Colorado and drove it back.

I knew more about the car than Kemp did when he bought it :)

Mixed results...basically wasn't worth the cost IIRC.

Our exhaust is pretty good in stock form...just add a set of aftermarket mufflers and you're good to go.


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