I have a 1989 Formula 242 ls and i want to throw headers on it simply because i want it to be louder and I've heard you can gain quite a bit of performance. I basically would just like for you guys to educate me on this. Im not really the mechanic and would like to know the pros and cons of putting headers on an engine like this. Thanks guys.

There will be pretty much zero gain in performance until you start getting over 500hp, and they won't be much louder. What you want to do is switch out the baffled tips for open units.

http://www.cpperformance.com/p-12589...haust-tip.aspx

is your exhaust already thru the transom or thru the drive? 454 or 454 magnum? either way you will not really see a gain just going to headers. Its great to want it to "sound better" but in reality are you accomplish is negative attention from the water cops and giving them another reason to pull you over and harass you. Then true headers like CMI's have a tendency to leak after a while, usually with the first tell tale sign being your motor ingesting the water and destroying itself..

Now a when doing a mild upgrade on a 454 mag motor such as a better cam, intake etc exhaust does come into play depending mainly on the cam as you can get reversion fairly ez with the stock manifolds, for that type of build(provided you dont go nuts with the cam) you can get by with a nice set of gills or stainless marine, both are still technically manifolds but will work much better and much cheaper tham true headers and can be found used at a decent price. I just picked up a nice clean set of stainless marine for my 454 for 500 bucks,

Good quick advice above.
You did not say if you have the silent thunder swim step or thru prop.
If silent thunder masi242 did an excellent write up in the formula section, I believe, with photos of work in process of great mods to his for better flow and sound. He did a great job on his!
If you have thru prop it is not a tough project to convert to a variation of the silent thunder.
Good luck.

thanks guys for the help really gave me something to think about, and yes i am running a stock 454.

You have silent thunder swim platform?

Fwiw - I put headers on my 502 Baja 272 and it made zero difference. Nada. Zip. But I switched out the stock baffled Corsa tips and it completely changed the attitude of the boat. It revved much better and sounds mean as hell. I may put the slip on silencers on it for lake use.

It was less than $200 and twenty minutes of work as opposed to $3k and a day of trouble.

so all you did was get new exhaust tips?

The tips were the last thing installed after the headers, but made the biggest difference. I had the stock Corsa mufflers which were particularly restrictive.

If you want a little more speed, save up and get manifolds, roller rockers and a little bigger cam and you will have some real gains. You may get a small increase from performance manifolds, but the cam and intake are needed also to get the air in