Quote:
Originally Posted by Boss330
Yes, aftermarket manifolds have some drawbacks that don't come with the stock manifolds. NVH, durability etc will probably suffer. But if you want more power, stock manifolds are often one of the restrictions that has to be modified to go over a certain limit.
Remember that the stock manifolds are not designed just for maximum power, but also to keep exhaust gas speed at an optimum even at lower revs to decrease lag. To accomplish this the tube diameter and design is a deciding factor.
On my second car (Sierra Cosworth) the factory had two exhaust manifold designs. The first one was for homologation purposes and is good for around 500hp, the later design which reduces lag significantly is only godd for around 400hp. But if you want to go beyond 500hp, you will have to go for an aftermarket tubular design to get enough exhaust flow.
Since the stock manifolds on the M5 is good for over 700hp (MHR) it would only be relevant to change the manifolds if you want to do an extreme M5 approaching 8-900hp.
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True, actually of what I've heard, the stock manifolds has something to do with fuel economy, which i think decreases the power. + those manifolds are wider and they were made for more airflow and something to do with the spooling.
Ill keep you guys updated anyway.
One more thing regarding the Turbo Upgrade, unfortunately the guys that upgraded the turbos didnt do a really good job.. So the guys at SR-R sent the turbos to another manufacturer... just an upgrade.. Or maybe a gt30x? not really sure..
