Did you try wiring them opened to see what power you gained from your RB exhaust and header? It would be interesting.

https://www.nopistons.com/forums/pub...>/rolleyes.gif[/quote]

well, I've had the header, presilencer, and Y pipe for a while now, with the aux ports still opening (at least some) with the stock mufflers, and the performance gains from the RB exhaust were significant. One thing that made a huge difference after that was cutting out the cover of the air box, you could really feel the aux ports opening in the high rpm with the improved breathing. I've since put on the RB mufflers and an HKS power flow 'intake'... it seems stronger everywhere but the top end, which I'm sure is because the aux ports are not opening anymore. I will probably wire them open sometime soon to experiment... but I did that once in the past and really didnt like not having any low end torque for driving around town. I have the RB aluminum flywheel as it is, so the loss of low end is really noticable and makes it a bitch to drive in town.[/quote]

I thought about cutting out that cover but didn't know if it would be worth while, so I was waiting until I'd install a kone filter directly on the AFM.[/quote]

It helped alot in 1st and 2nd, but the top of 3rd-5th were weaker, I believe at the higher speeds with the airbox in tact there is a slight ram-air effect, cutting out the cover hurt this, but the top of 1st and 2nd gear were extremely stronger with the top cut. Best would most likely be an HKS or K&N high flow unit replacing the airbox, but fabricating a (cold air) box to go around the high flow filter with some large ducts routing fresh air from the front of the car, so you can get the raim air effect. Of course, this is really just a big deal if you're NA like me https://www.nopistons.com/forums/pub...IR#>/smile.png Oh, it also got a bit louder with the cover cut open, and I had a K&N drop in filter when using the stock box btw.

Wired the aux ports open today by removing the acuators and putting some twist ties to good use. It pulls like hell > 6k, all the way to 8k where I force myself to shift, but it hurts like hell since it's still producing gobs of power compared to the rest of the rpm range, feels like a turbo kicking in. But with the aux ports wired open everything less than ~5k is plain shitty compared to aux ports closed. There are probably major gains possible on NA 13B's just by tuning the intake, variable length intake runners for instance 787B style would be pimp https://www.nopistons.com/forums/pub...DIR#>/wink.png When I do the rebuild I'll have to find a VDI from a later 2nd gen to replace my extension housing and port/polish the rest of the intake. If I get a later lower manifold would I be able to convert to vacuum activated aux ports? anyone?

I was wrong when I was talking about vacuum activated aux. ports, I was mistaking with something else (dac corrected me on this), they are activated with pressure from the air pump, 6PI solenoid valve and a ECU output. But it gave me an idea for something else, I'll be back with explanation later, when I'll be doing tests.



BTW, I guess the later 2nd gen was 15hp stronger partially due to the new intake.