05 CV8 back boxes

[cv8 mike]

Hi all,

If I were to remove both back boxes and get some tail pipes made up for each side to join back to the stock flange joints, how loud do you think it'll be?

At the moment the system is stock with both pipes from the cats going into a central silencer before exiting into individual tiny little boxes and then into the final huge rear back boxes.

Just curious, i dont want to go and spend the money on a full system because I dont plan on having this car for more than a year.

Cheers

Mike

Edited by cv8 mike on Friday 3rd April 19:55

[Drew SS]

just take the middle ones out will sound just like it should

[V88Dicky]

Drew SS said:

just take the middle ones out will sound just like it should

^WHS^ Thats the route I'm taking at the mo, resonator removed (replaced with H-pipe) and the two small centre boxes replaced with straight thru pipe. Lovely low rumbly old school muscle car sound, total cost around £200.

[granada203028]

I would be interested in a little more "classic" sound without risking refinement. Present system does hum a bit 1000 - 1500 rpm. Picture is the centre system, removed when I changed my gearbox 18 months ago. So this is replaced with strait through pipes with a cross pipe at the front common box position?

[cv8 mike]

Some good info there cheers guys.

The main reason I was on about removing just the rear boxes is for easyness really as its not touching the rest of the system and can go back to normal by just bolting the boxes back on.

[granada203028]

Drew SS said:

just take the middle ones out will sound just like it should

Drew SS knows his stuff. I bought a used centre section and back boxes off Ebay for £45. This system already had no centre boxes but in all other respects is identical to the original. I don’t know the history on it, I bought it from a guy in Aldershot. I didn’t meet him, my brother collected it. The guy didn’t have a Monaro, bought it of eBay himself in preparation for getting a car, but never got one. Courier labels on them are dated May 06 delivered to an address in Surbiton. Generally it is in better condition to my 4 year/43K original though more sooty in the tail pipes.



As the build and detail construction is so identical to the original I think it is a genuine GM system for Australian CV8s, and the extra boxes is another British noise emissions bodge. How ironic given I changed my gearbox to correct another supposedly noise emission fix. Maybe an Australian correspondent can confirm (tim the pool man?).

I tested several combinations attempting to quantify the changed sound by recording on a laptop. Unfortunately the lap tops AGC has compressed the differences some what:

Stock with centre boxes:

http://home.clara.net/gasturbine/Stoc

Original centre with new back boxes – slightly louder:

http://home.clara.net/gasturbine/NewB

Original centre no back boxes – not ear splitting, quite thrummy/hummy:

http://home.clara.net/gasturbine/NoBa

New system – much more woofle, generally louder but no drone. Windows up cruising just as quiet/refined as before – tyre/road noise still dominate:

http://home.clara.net/gasturbine/Newb

I’m surprised how much the car spits and pops. Always does this though perhaps less when fully warm. Perhaps I need a remap after all! I don’t think there is any noticeable power increase.