3400 ported exhaust manifolds...worth the cost?

[Starglow]

I'm doing a 3400-3500 engine swap in my '99 GA and after much research have come to the conclusion that there are no reasonably priced header options available for my project that won't have issues or rust out in a few years.

However, I'm also hesitant to restrict the 3500 performance by reusing the 3400 exhaust manifolds even though that seems to be the best cost effective alternative at the moment. Then I saw that WOT-Tech offers ported 3400 exhaust manifolds however I can't find any reviews from anyone who actually installed them.

So my question is will these ported 3400 manifolds be beneficial to a 3500 engine swap with unported LIM/UIM or heads and if so, how much improvement can be expected over stock 3400 manifolds?

It would be nice to just use the 3500 exhaust manifolds, but there is no exhaust system components available to support that when doing a swap into a GA. I can't afford to drop $900+ on the Milzy headers at the moment, so I'm looking at the ported 3400 exhaust manifolds as an alternative solution. BTW, I'm using the stock 3500 UIM if that matters.

Feedback and suggestions would be appreciated....Thanks!

[Superdave]

you can use the 3500's manifolds, either style. The 3500's log manifolds (look just like the 3400's on the outside) are probably about the same if not a little better than ported 3400 logs. The "header" style 3500 manifolds from the malibu's are really the best cast iron manifolds GM made for the gen 3 60v6. They flow excellent and are pretty easy to set up in any car.

In your Grand Am you could do something similar to what i did in my old 3400 swapped Jbody. In the pic you can see that for the front i used some mandrel bends to U the pipe back up and it follows the stock crossover routing. In the back you'd just run the rear downpipe off the manifold and then Y the 2 together with a standard 2:1 collector. It'll take some work but if you have a few markers, a hack saw and a welder you can make something almost as good as shorty headers for less than $200. You'll need flanges to bolt to the 3500 manifolds, i think TCE was making them at one point, if not then a local machine shop would do it for pretty cheap.

[Starglow]

Thanks Superdave.....! Which GM cars had the 3500 log type manifolds? They might work assuming I can get a crossover pipe to fit if I can't use the 3400 crossover. Around here I'm sure I'd end up paying at least $700 for an exhaust shop to custom fab something up so the Milzy headers would be a better option in that case.

[SappySE107]

Pacesetter are the cheapest headers available. We won't have ours ready for the N body for a few more months most likely, but the price won't be much different than what MMS has now.

[HOYS]

I'd say that ported exhaust manifolds are nice, but not worth the price.

Save your money and buy Pacesetter's at the lowest end, Milzy's or WOT's (when they come out.)