I've been browsing through the Time Slips/Dyno section, and everybody that's N/A with standalone doesn't seem to break 200whp without custom intake manifolds or wild porting. I have an S5 N/A engine, mildly streetported ("smog-able"), and for a while I'll keep it as stock as it is (stock ECU, mild exhaust upgrades) so as to not have lots of power when I start learning the local racetracks. However, further down the line I'd like to increase power substantially (but not too much for an N/A drivetrain to hold), and doing it N/A and while saving some weight would be a plus.

Simply put, I'm wondering just how much power there is to gain from switching from the stock intake manifolds to, say, a side-draft DCOE-style 45mm twin-throttle body setup. I would retain the stock LIM, use a Mazdatrix UIM and get a throttle body setup from TWM induction (that's what I was thinking, anyways).

I know there's plenty of room to improve on the exhaust side of the NA FC, but I was wondering if anyone can comment on just how much improvement can be made on the intake side.

 

From what I hear the stock intake manifolds suck with a streetport. Kahren claims his aftermarket intake manifold will be good for 20HP, maybe it'll be the same with a properly built intake manifold with your application.

I'de PM him anyways.

 

With a properly fabed manifold you can port away and run ITBs and I will suspect much more impressive gains.

Expect 800 to 1500 for a custom mani + your ITB's not to bad.

I am going to be fabing one for a friend with stock TB for a large SP here shortly. I will post numbers before SP after SP and with custom mani. The SP also contains no delayd closing time.