Exhaust mods on the cheap

[L2VXR]

Having recently picked up a standard cat back VXR exhaust system
from my main dealer for £75 & various lenghts of 63mm stainless tube/bends
from another source im thinking of making up a custom exhaust but im not sure
which route to go
i was thinking ;

1. remove first silencer box and replace with an X pipe
2. remove 2x centre boxes and replace with straight through tube
3. fit 2x electric cutouts that vent under/eachside of the diff,giving a
straight through short system when open and through the original rear boxes when shut


or

1.remove the first silencer box and replace with an X pipe
2.leave the centre boxes alone
3.fit the cutouts, so it super quite with flaps shut but rumbles when open

I don't know if this would affect performance good or bad although im not
after any gains,but i wouldnt want to damage anything either
it's just to make me smile when i flip the switch

have any of you modded your standard exhausts?
if so what were the results like?
any advice?

Yes, Yes I now i should just go and get the wortec stuff
but were not all made of money

[J. J.]

How about just changing the rear boxes - get some smaller lighter boxes with different end pipes. You then have an opportunity to put a more modern end such as those on the VXR8. The std rear boxes are far too heavy with too much silencing material. Wortec exhausts have far smaller rear boxes.

[ringram]

Pipe diameter and muffler flow are important if performance is an issue.
I think its about 112cfm per sq inch and you need 2.2cfm per engine bhp for optimal results.

First resonator acts as an expansion chamber normally which allows exahust pulses to travel back to the port, so losing that may be counter productive, unless of course it flows like crap.

Best power stock is probably 2.5" twin system with no flow loss on mufflers etc, plus an expansion chamber. Large cats can act like chambers on occassion.

Lots of nice reading on popularhotrodding website, just search for "exhaust science".