26ZX Donzi

I have a Gen VI 502 with a Livorsi Marine "Extreme Supercharger" in my Donzi. This system is built around a Vortech compresser, intercooler (Livorsi Design), upgraded fuel system and ECU upgrade. It has improved the performance on my boat from 64 mph/gps to 80 mph/gps (nice cool day right before winterization).

Is it worth it to put another $1500 to $3000 for an exhaust upgrade? It still has stock Merc manifolds with Corsa Q&Q system. I need to keep some type of switchable exhaust to keep neighbors, and more importantly, wife happy.

At present I am considering Stainless Marine (can use existing Q&Q), CMI with their switchable system ($$$), or a used set of Gil's (that I have been told have tailpipes that will work with my Q&Q).

Thoughts? Experiences? Any likely noticable improvements?

Tim

Pure Energy

Stock Merc. exhaust is good to about 600 HP. Silent choice is ok at idle speeds, but not when on plane.

Airpacker

I ran stainless marine manifolds on a 600hp 540 with corsa captains call cut outs for years with no problems what so ever

Tantrum

If for nothing else I would change the stock exhaust as cheap insurance. Mercury has a WAY bad design in their stock riser gaskets. I personaly spent about 6k rebiulding and another 2k buying a new exhaust when my motor suffered reversion from a leaking riser gasket.
Im sure if you check around you will find countless other people who have had this happen or know someone who has.
Change it now, before its too late.
As for performance Im sure an aftermaket will let your motor breath easier. The more air out, the more air in.
Which one should be your only question.

26ZX Donzi

Need input...
or is there a definitive answer?

formula31

What Tantrum said is valid but in my experience, you'r good for 10 years in fresh water. Riser gaskets do suck but they have a new design out that should be better. I also believe that aftermarket manifolds/headers are critical on built, NA engines. I dont think they do a lot on stock or mildly blown engines.

I use Gils, lighter, good power improvement to 480 hp NA but wider (real problem on twins) and a pain to get at the plugs.

Smitty

Tim,
More air in equals the need to let it out. I run a set of Imco powerflow aluminum exhaust manifolds w/stainless risers with a Corsa system also.
Do they add any power??? I picked up 1 mph on a stock motor and now with the Whipple I am sure they are helping a little. I have never dyno'd the motor so I cannot say if they actually increase H.P. but they sure do look visually larger and provide a smooth path for the exhaust to exit.

Maybe Dennis Moore can chime in and help with some real world results he has seen. I thought not to long ago he did a magazine test on some manifold testing. Try doing a search for it.

One thing I am changing this year is my exhaust tips. I have those black Salisbury flappers and I am going to replace them with longer angle tips with internal flaps. I had those on my Scarab and I know the exhaust was louder so I am guessing the current ones restrict it a little. What kind do you have on your Donzi??

I am pulling my motor out soon so P.M. me if you want to take a look-see.

Dave

totalmp

Bigwavz is right. To increase HP, you have to be able to get out everything you put in. In some supercharged applications, your exhaust can restrict the amount of air and fuel an engine can flow. This means you aren't getting the full potential from your blower. Call me if you need anything, as we can put you in a full system that works w/ silent choice for about 1700.00 complete w/ stainless 4" riser.

Stephen

Big Boys Toys

Tim,
Take your time looking at exhaust manifolds, you have several choices Stainless Marine, Gil, Impco, Stellings, and CMI, and a few more I have not mentioned.
They all make a good product improve performance and are all pricey. The stock iron manifolds do a descent job but have their limitations.
I have worked with Stellings mainfolds, Stainless Marine, Impco and CMI. The best system available today and probably the most expensive is the CMI system.
Go slowly do your research and then make the purchase.
Any one you deside on buying looks much better than the stock application.
Keep in mind you will also have to play around with hoses, clamps, shift linkage, throttle linkage, remote oil filter, water fuel seprator and what ever else bolts onto your stock system.
Post what you decide to do.
Good Luck
Brian

barry

i may have apair of uses stainless marine manifilds with crome 4" risers that also fit the corsa quick and quiets for sale. call me at 7124-864-7730 ext 112 or e mail me at [email protected]