HP manifolds

[jusglazin]

What is the difference between the hp and regular manifolds for a RB engine? Are the regular ones worth using or should I look for a set of the HP's for a street 440 with app 400 HP?

 

[Budnicks]

I have used both styles, the HP style will give you a little bit more power over the std. manifolds the runners are split farther into the manifolds to stop reversion on exhaust pulses & have a 2 3/8" exit, but some 1 7/8" TTI headers will give you way more HP/TQ than either of the stock iron manifolds, they are a bit pricey but so are HP manifolds now.