Rear Mufflers and pipes

[Kiwi.in.aus]

When I bought my Celsior someone had stolen the rear mufflers and had replaced the mufflers with a 1 and 7/8's inch straight piece of pipe from about 3 inches after the last two bolt flange .
I removed the straight pieces of pipe and had it just coming straight out just after those flanges , there was hardly any increase in noise at all , just a little bit but bugger all !!
Still can't hear it from inside or standing beside the drivers door for that matter !!
This decided me to conclude that for noise abatement no rear mufflers are neccessary .
So as close to the end of the flange as I could [ about 15 mm , just enough for me to get a TIG weld in there ] I have used a cone and gone up to 3 inch pipe then around the 70 degree bend and straight out the back all in 3 inch .
Havn't had it out on the road yet but it looks very cool !!
My question is , with not running the rear mufflers can anyone see this having a detrimental affect on anything , taking in mind that the rear mufflers don't seem to do much as the car is still quiet .
All input greatly and wonderfully received !!
Actually would prefer if there was a bit more sound !!

Regards...Rich

 

[V8TOY]

i took my back mufflers off and it was sweet only a slight noise increase.

 

[JBrady]

I have ran many miles both with and without the rear mufflers. No concern except a slight worry if you were to sit idleing for an extended period due to fumes. With extension pipes that is not an issue.

3" pipes will not do anything for performance. I am surprised you ran them from the rear flange as they must travel under the differential limiting ground clearance. Otherwise, no problem.

You are correct on the noise abatement. The middle two mufflers really drop the dB's. I pulled those off leaving the center resonator and pipe and the car sounded like a loud Corvette at idle. Really nice actually. Driving was pure hell as the noise was deafening.

 

[Kiwi.in.aus]

Thanks Mr Brady , no issue with clearance as it's only the actual mufflers themselves I've replaced [ which i didn't have in the first place !! ] so that is actually after the diff mostly , was actually going to go with 63 mm diameter tubing and bends but a 63 mm 90 degree 316 S/S bend was $36.00 and a 3" bend was only $18.00 !!
The tube itself was also $10 a metre cheaper in 3" .
So 3" it was then !!
I realized that power wasn't going to be increased , really just did it cos I can [ I have my own TIG welder ] and had no mufflers and they are not needed , what I really want to do is get some of your manifolds and then run a twin side by side all the way through to where they go out to each side and then 3" for the last bit out to each side .
What I don't want to have to do is play with what size pipe and what mufflers to run , don't have to run cats so won't , but don't want it to be drummy or too loud .
Any advice on the configaration to run ??

 

[1992/SC400]

What happens if I remove the cats and resonators(test pipes in place of the two manifold cats and remove the center cat) with some highflow mufflers in the rear. This is what I want to do over Christmas but want more noise and power. Would this help?

 

[SCV8]

It all helps, one thing I noticed with the stock systems was that there is an intended restriction at the Y pipe that contributes to the quietness a bunch. Just getting rid of that will help the flow greatly, along with creating some more noise of course.
The stock dual cats aren't very restrictive when used with the stock manifolds, and would likely be a waste of effort to remove. I can't say much for the center cat, as here in the states only cars sold in California had those, the rest had resonators in their place.

 

[1992/SC400]

So I would only be helping the cars performance by removing the cats and resonators. Is there a bad side to doing this besides its unlawful (I'm almost sure I would not drive it on public roads...promise)? I just want to know if there is a down side to doing this as far as performance goes, and if I need to do anything else along with this.

Thanks