Well for awhile now i have been running 4499 pacemakers, 2.5in high flow cat and a single muffler 2.5in redback sports exhaust.

Having all this fitted to my EL sedan caused high rpm power to improve but i lost alot of low-mid power.

Took it to an exhaust shop in brissy this morning who were going to fit a set of pressed bent extractors but decided to try putting a pressed bent 2.25in pipe from the back muffler over the diff and out the a***.

The reason behind this was this is the slowest point of exhaust gas velocity and by decreasing the tail pipe size it will inturn increase exhaust gas velocity and backpressure at low rpm.

Anyway they did this and we took the car for a drive and it worked, all my low-mid power is back and it also got rid of droning at 80km/hr.

All up it was $88 and the bloke said they often do this mod to auto cars that are producing between 95-120rwkw that have 2.5in exhaust and have lost power down low.


Cheers.......................

Has restricting the diameter of the tail pipe section effect to the higher portion of the power band tho...as a result of improving the lower rev range power ? .... sounds like a good idea tho and obviously works

power at high rpm is still there, although haven't got out on the highway yet to give it a proper strap above 100km/hr overtaking etc.

It also accelerates alot smoother now all the way up through the rev range.

Wouldnt there be any trade off?

Cant have you cake and eat it too.

Id guess that the smaller pipe increasing backpressure at low rpm would produce even more backpressure at high rpm.

An exhaust bloke was fitting a resonator to my eb v8 when i had it to quieten it up. He tried to fit a 2.5inch resonator to the 3inch system.

I almost whacked him over the head with the resonator. His justification was that it would make it quieter like I had asked. I told him that I asked for a 3inch resonator so put a 3 inch one on. He stood there dribbling and with an embarrassed look on his face.

Whats the point of having the 2.5inch if it breathes like a 2.25 inch?

Just ring a good exhaust shop in your area, i am sure they can explain it too you.

Is the top end power definately still there? Do you think advancing the cam would have made a difference?