Basically a few things


1. 9886 outperforms every single modern EFFRA approved pipe, more torque and more HP then every single one of them ....I have been testing everything I can get my hands on and with both onroad and offorad applications the 9886 makes more power then everything....So if in doubt just use a 9886 and tailor the manifold length to the engine, you will have more power and torque then any other combo you can buy from any of the manufactures bar none..This is universal on all engines too...not just Nova

2. Its all about the manifold !!!! matching the manifold length to the engine is critical... Basically sticking a offroad manifold onto a onroad engine kills its power..in a GT car with a offroad manifold you should not run onroad engines as the power will be down compared to a higher timed offroad engine with the same manifold... For a onroad engine to make its proper power and powerband it needs an onroad manifold........IMO this sort of makes some of GT engine rules arbitrary ..... one of my simple modified $300 offroad engines would decimate every single high end Onroad engine money can buy as long as they are both on a offroad manifold....swap to the onroad manifolds and of course it all changes !!!