ccarloss

What exhaust would you recommend/prefer on a hp500 carb? We may need to replace the GIL manifolds. Stainless Marine looks like a nice setup. Of course CMI is nice but a good bit more expensive.

Does anyone know if there is a performance difference between a good manifold and CMI's.

Thanks!

krypto 1 in CT

did you check out the cyclone manifolds by hardin marine they are in they cp performance catalog.they are tubular sainless steel.there is a set that are direct replacements for the gill/merc manifolds so you dont need to do anything with risers just bolt them on with your existing risers.they look real good and are suposed to make a little more hp/tourqe though i would like to a see dyno sheet comparing them to the gills.show me 15 to 20 hp gain from 4500 to 5500 rpms and i would buy them today.

IndianaHeat

a less expensive option is lightning headers

ccarloss

Thanks for the info. I did take a look at the Hardin GIL replacements. They seem about the same price as the CMI's.

p4-33

I bought my Fountain 10-Meter already rigged with HP500 carb motors running IMCO Powerflows. The advantage with these is you can set the motors at 33" on-center, with about 1/2" clearance between the manifolds.

The disadvantage is once you're at 33" on-center, you pretty much rule out using other exhaust systems. Most of the specs I've seen require minimum of 34" OC, and I think CMI needs 35" OC. Where are your motors currently set?

Also, does anyone have any HP gain/loss specs between the different brands (CMI, Lightning, IMCO, Gill, etc) ? I'd be interested to know whose headers perform the best, with some real numbers.

Thanks,
Brian