[Massive Type IV]

Been there- done that...

If you don't have a 4-1 collector, or a 4-2-1 collector you are literally pissin in the wind.

The firing order and scavenge require it. When I did this I could not get the engie to tune, it made no power and it ran hot as hell.
With a TIV, exhaust is everything. I have seen 5,000.00 engines with 200,00 exhaiust not make as much power and run hotter than a 200 dollar engine with a 2,000.00 header- literally.

Due to the exhaiust ports of a TIV head, they are mucho sensitive to backpressures, scavenge, and volume. As the camshaft duration on the exhaust side changes this increases.