Summer89

Hey all first post here and I'm looking to learn and tinker a lot. I've searched all over Google with no definite answer and many posts leading back to here. So I'm hoping as time goes on every one can share some knowledge as some of you have probably doing this longer then I have been alive. So I have a mild built ( Aluminum heads roller cam intake carb) 89 454 true mag maybe 400- 425ish hp and im still on stock mercruiser manifolds I also have stock mufflers. First i would like to know are the mufflers "power robbers" as i do like not having a headache after a day out. Secondly eventually I would like to add some bit more performance type manifolds to it to get the last bit of power from my set up and to help it breathe better. Im curious as to what's a decent not break the bank manifold?
Ive read into the 496 manifolds being a pretty mostly simple affordable swap and comparable to aftermarket on the 454s. What I don't know is which kind? Aluminum or iron? And whats a full wet vs half wet set up. I run in freshwater and use the sea pump with a Hardin crossover setup. So I have no idea how the plumbing would work. With these on would i still be able to use mufflers? Also on the 496 manifolds what do I do for the shift cable bracket?
Are the 496 ones the way to go for the poor man's manifolds, or are there other comparable priced used ones such as stainless marine, imco, or.......? I know it's a lot but I appreciate any help or pointers.

articfriends

Im drawing a blank when it comes to stock " mufflers", can you post a pic? Either way with a stock cam on a stock 454 if you gain 50 rpms from switching your exhaust youll be lucky especially since you want it quiet and its muffled.

Summer89

I have a roller cam. Not the stock one. I can't post pics or url yet because im new. So here's an ebay item number for example of the mufflers 195552713746

PQ290Enticer

I looked at your ebay muffler and I am assuming this is between the manifold and exhaust tips? I was expecting to see a "muffler exhaust tip". Can you replace those mufflers with rubber hose? You would at least get an idea of what the mufflers are costing in terms of performance. You can post 8 more posts here titled "Post 3, Post 4, etc. then you can post pics. I know a pic would go a long way for me. Welcome to OSO.

Summer89

Yes they go after the risers before the tips. I could replace with hose just to see. I didn't know if anyone knew about these right away. Are you saying make 8 dummy posts on my thread to get to 10?

Helmwurst

^^^^^ I had those on a set of 454Mag's a long time ago. I did take them off for a season and noticed very little if any gains and it was a little louder, but not much. I put them back on when I sold the boat. They are a black box looking things, if I remeber right they had the Mercruiser logo on them.

Summer89

yes the black boxes. Good to know they don't take much or any power. Now i just need to figure out of they fit with performance manifolds

PQ290Enticer

Yes to dummy posts

Helmwurst

I would not put the muffs back on with performance manifolds. The stock Merc style have a pretty restricted outlet. If you move up to Gil style or other, it will have a larger outlet, like 4" or so. The mufflers will likely take away from any gain on new manifolds. If it is too loud and you want to quiet it down, find a set of external mufflers to fix that. JMHO

Summer89

Makes sense. I thought the merc mufflers were 4" i could be wrong. But excuse me for being dumb but what are Gil manifolds?