Are you running a nitrous engine and having a problem burning plugs? Or, do the plugs in your naturally aspirated engine look different from cylinder to cylinder? Your manifold could be the culprit.
All stock manifolds have runner imbalance, which can be fixed with PROPER porting. As an example, a 302 Victor Jr. manifold has average runner flow numbers ranging from 265 to 290 C.F.M. in 'out of the box' form. This is a 10% difference. The unbalanced runners can cause a myriad of distribution problems and can even cause severe damage to an otherwise perfect engine.
Panhandle Performance addresses this problem by balancing all runners within 2%. This is not done by matching the runners to a specific gasket size (like the majority of shops do) because doing so may magnify the imbalance. Panhandle Performance modifies the cross section of each runner opening to get the needed flow numbers. This is backed by our state of the art Flowbench, from which you will receive a sheet listing each runner's flow numbers.
In order for your manifold to have the best possible fit and finish, it is highly suggested that you send your cylinder heads to us for a trial fit on an engine. This is mandatory on all Stage III manifolds. If a spacer or plate nitrous system is to be used, we will need the plate/spacer as well.