Exhaust Manifold upgrade

[tucson_boat_guy]

Whats going on.
I am looking for what to do with the exhaust on the boat I just bought. I have a stock 454 with a Bravo and stock manifolds. I am guessing they are not very good since most boats I see with I/O's run something different.
It is also still running through the outdrive. I don't want it super loud but it would be nice to get some more power out of it.
What do you all think?
Do any of you have any better than stock exhaust you just upgraded and maybe want to sell?
I appreciate your input on this.
Thanks all

[scarabrick2]

I have some exhaust tips good up to 600 hp. Imco
http://www.imcomarine.com/pages/exhuast.html
Scroll down.... MEGA 704......
Don't have manifolds for you, sorry.
check the spam or Offshoreonly classifieds.

[CONCEPTMARINE]

Exhaust Upgrade Is The Best Thing You Can Do To Get More Performance. But It Is Best To Run It Through Transom. We Have Used Eddie Marine & Imco They Both Work Great.

[justfloatn]

I did the same up-grade last winter. Stock 330HP 454 through transom. Changed to through hull. I went low budget Revolution Marine because I don't plan on building a High HP motor. I was able to raise my prop from a 21P to a 24P and gained 6MPH. The low and mid range acceleraton is the biggest improvement area. I had to run the S pipes to get under my swim step. Get the aluminum ones from IMCO,they are alot cheaper. You can find muffler tips on E-bay. The rest is hard to find on e-bay plus I would not trust a used manifold when new is around 1,000.00. I have to warn you If you have to remove the stock Y-pipe for clearance it is a bitch. You have to pull the motor or be able to move it forward about 6" to get it out. Also look at your stock risers, If they say stainless steel on them you can sell them for $100.00 to $150.00 on e-bay. They are a discontinued part.
It's worth it, Do it!!

[tucson_boat_guy]

This feedback is great. I have a stock 454 I am guessing 330Hp. The only plans I really have right now is trying to make this boat plane faster and run better. I know exhaust is a big deal with any engine. I want to remove the stock Y-pipe and will be pulling the engine to clean everything up this winter.
What manifolds to you run justfloatin?
I would like to have a set that looks nice and frees up some space around the engine. I can bearly see it with all this stuff around it.
How far under down on the transome can I put the exhaust and still be OK at idle? Does anyone know?
What is the best way to cut the holes. I am guessing a simple hole saw with tapeing the area off will work.
Are there tips I can put on it to keep the noise pointed toward the water to keep it quiet while on plane?
I am a jetboater and run outboards in the past so this inboard performance thing is new. Thanks to all replying. This is good stuff.
Is anyone in Tucson with a performance I/O that I can come take a look at to see what is really involved?
Thanks