Aluminum Exh / power gain ?

[Jim Nichols]

I have a 85 Merc 260 hp Alpha with cast iron exhaust and risers due for replacement. Should I upgrade to cast aluminum? What can I expect in hp gain and longivity? Which brand is better ?

[SouthernComfort]

I replaced my cast iron manifolds and risers just recently with IMCO Thumper Power. They are a perfect fit! Yes, I did get a performance pickup. The engine has better tork and I picked up 200 rpm.
I boat in the saltwater of the gulf and do flush the engine every time I use it. With care and proper flushing I believe they will last a long time. I bought them through Teague marine.
Bobt

[Jim Nichols]

Thanks BobT. Do you have thru hub or transom ? Mine is thru hub. Do have SBC or BBC.

[SouthernComfort]

Jim, I have thru hub and a SBC.
Bobt