New Exhaust system - help

[CoronaC]

Hey, im thinking about getting a exhuast system for my celsior and was just wondering what would a good size piping be for stock car, is 2.5" too big?
Whats the stock system size?

I'm after a system with a nice rumble to it but isnt loud as **** and hopfully be a decent improvement over the stock system, power wise.

My idea for the system is...
Replace the cats with better higher flowing ones,
Into Y-pipe,
Another Y-pipe,
Into Large Hi-flow Resonators,
Rear Mufflers (Something to keep it kinda quiet)
All done with 2.5" piping

Would this be a loud, droning sounding system?
Anyone done something similar?

Cheers
Chris

 

[madmont]

There is nothing wrong with the stock cats.
2.5 inch pipe from the cats to the Y is too big , some recommend 2.25 inch
I use 2 inch which I consider to be adequate and gives good low down torque which you will lose if you use 2.5 inch pipe. After the second Y some people use bigger pipe .I use a single 2.5 inch pipe after the merge with 2 ss straight through mufflers. Not noisy or droney, works for me.

 

[Peewee]

With twin 2.5" all the way you are going to get some serious drone.

twin 2.5" = single 3.5"
twin 2.25" = single 3.2"
twin 2" = single 2.8"

Personally I'd go twin 2.25" off the headers, then through twin 2.25" cats, then either an X-pipe or dual Y-pipes with a 3" centre, then step down to twin 2" for the resonators and mufflers.

 

[LSKid]

i got a full system done on my LS400 with custom headers & stainless cats through 2.25" system, to X pipe throught twin resonators & out straight through 2.25" mufflers & sounds quite good!

 

[CoronaC]

So 2.25" is max size i should go and drop down to 2" after 2nd y-pipe?
How much difference would there be if i stayed at 2.25" after the y-pipe?
Another thing, what better for what im after Y-pipes or X-pipe?

Cheers
Chris

 

[LSKid]

Depends what your after & if your going to be using factory headers or aftermarket.

My system is a full twin system with 2.25" piping all the way & X pipe in the centre!
Im not sure why people use a Y pipe on V8's because it destroys the sound, peforemance wise they apparantly are restrictive pending how your headers are set up. eg: pulse tuned or not!
Do not get a merg pipe because they cause a massive tornado effect in the exhaust, & can sound crap as a few friends have found out!

Good luck