Hey, I'm looking at upping the power level of my 5 litre down the track, but not doing things all at once due to limited funds. I'm still running the E7 heads at the moment but I've got a K&N Filter and an explorer manifold. At the moment, I'm running a twin 2.5" system with 2 mufflers (one per bank) and it merges into a single outlet above the diff. Is this setup good for power, or am I better off to run a Single 3" system with 1 muffler, I also want a bit of a note, but I dont want it so loud that it's gonna be cop bait. It's plenty loud enough the way it is, it sounds pretty tough now, but I'm just wondering if a single 3" would be better? Even just changing the single 2.5" tailpipe to a 3"?

Thoughts anyone?

Gab

my cousin has a single 3" all the way and it sounds droney and shlthouse in the car.

i would stick with what you have and possibly run the twins out the back if possible.

2.5" dual with 11" magnaflows and high flow (100 cell) cats

No bigger than a 2.25" twin system. Twin 2.5" chokes top end. On an E7 headed car, I'd go single 2.5".

going bigger won't 'choke' engine at higher RPM, in fact will let it breath more.

However, going to big will sacrifice lower RPM torque due to lower gas velocity. Going that tad bigger such as 2.5" dual will allow you to make improvements to engine along the way, such as cam and heads to compliment exhaust without having to change up again to a larger bore system. my thoughts.

Twin 2.5" flows a fair bit more than a 3"...

It really depends what your long term goals are. I have a single 3" and I think my long term goals only really extend to wanting consistent 13.xx second passes and I see absolutely no reason to go bigger on the exhaust. I probably wouldn't even if I was running a blower, but that may well just be me.

It drones on part throttle over maybe a couple of hundred RPM somewhere around 1700 but that's probably more the cheap muffler...

The point being too small for your end goal and it will cost it top end, too big and you'll lose some torque... and also probably some top end.

As for the sound... extractors and cam have a lot to do with that. Generally speaking, both will make it louder and deeper.