454 mercruiser ex manifolds
 

Who has the best price on these?? I need to replace a set on a cruiser.

Get a set of used freshwater manifolds. They're generally like new and they're about 90% cheaper ($150). GLM also makes some cheaper knock-offs, but I've never used them.

Is your exh. 3" or 4"?

Glm
 

I believe GLM makes cast aluminum replacements (semi tuned) with runners almost to the risers.

Mercruiser 454 manifolds by Dennis Moore
 

Recently we (Moore Performance) received a dyno sheet from Wyo Tech marine school in Daytona Beach. A customer supplied the school with a stock 454 (with stock Mercruiser manifolds) and GLM replacement manifolds. The replacement GLM manifolds increased performance by 12 horsepower at 4600 rpm over the stock manifolds.
We were totaly unaware that the test was being performed
and were pleasantly suprised by these unsolicitated results.

We have tested the GLM manifolds ourselves and have seen similar results on the dyno.

This increase is from a replacement manifold that has the same dimensions as the stock Mercruiser manifold (a direct bolt-on replacement) with internal manifold runner improvements. These improved exhaust passages are a result of using an ultra modern/hi-tech foundry that utilizes "Lost Foam" casting for improved quality.
Not everything made in China is junk. China has some of the most modern foundries in the world.

Dennis Moore
[email protected]