Those manifolds are great but they are so efficient that they will lean out your engine and the ECM will need to be reprogrammed or, at the least, the fuel rail pressure will need to be increased to compensate. I hate to be pushy here, but my new manifolds are really a high quality piece at a very reasonable price. I really believe in them! Check them out at www.mooreperformance.org
Sincerely
Dennis Moore

Roby,
The name of the company that now owns the tooling for the KEPP Manifolds is Brummett Marine. The number is 626-792-6410. The person you need to speak with is Carson Brummett.

Good Luck!

Check out Teague's pricing on the lite series from Custom Marine, very reasonable.

I agree with Kaama's first post. The KEPP exhaust will do little now but will respond well with other changes. Also you will be spending a lot more than a "little" over Merc stuff. Also, the peanut port heads on your motor will offer great low end torque and great midrange response. I installed the big valves and pocket ported a set and they worked very well. The peanuts start dropping off over about 4600 but do very well up to that point.

If your boat is running a 25P Mirage at 4800RPM you should be going faster than 61MPH, with a 22'Scarab.

Dennis/ I also thought additional fuel needed to be added with 415 hp MPI and KE's pipe but a neighbor put some on, no changes to the motor and made out ok. Would go out and peg the stick for a few minutes at a time and never had a problem. I believe he also picked up some rpm in the change??

Whiteknuckle,

Not trying to get off topic here, but are you saying that he "peanut port" heads are still only good to 4600rpm even after pocket/bowl porting and installing larger valves? Just wanted to clarifty---thanks. :)

Kaama,
That seemed to be the case with the peanuts. However, it may have been some other issues too. This was what I observed with my engine. Different cam or induction may get a better result at higher RPM. I find it amazing that everyone just wants to write the peanut port head off when actually they are capable of out performing the others up to a certain point. Right now I went with a set of 049 heads I bought from Fred. I still have that set of peanuts in my garage, I might put them back on one day!

Yes, the 049's are very good too! I agree, with a little work the peanut ports are really some very good torquey heads for a 454. Do you remember what cam you were running in the peanut ports?

Bob, that is interesting. I would bet that on a hot day or at a higher elevation the engine probably will run fine due to poor air density. A lot of our testing in Los Angeles is at sea level with good air density. He better watch it if the temp cools off and he gets good air!
Thanks for the input.
Sincerely
Dennis Moore

Okay are we talking about the Vortec heads? Because the 1998 7.4 MPI does not use the small ovals

Roby