Topplayer

I got 410whp ap1 stock header 60mm test pipe with a hks exhuast which is 60mm

APoner

438whp e85 n1220 3.2"

Stock header
63mm test pipe
60mm dual

99SH

There's a false perception that bigger is always better. It's all about efficiencies.

1nate7

You can easily achieve those power levels with stock or aftermarket 60mm exhaust, it's all about the pulley size. I would have to search, there is at least one documented case of swapping between 60mm and 70mm exhausts. From what I remember, there was a very small difference in overall power. The difference is that the larger exhaust makes the same power with less boost. In theory, you could run a smaller pulley to achieve the same psi with the larger exhaust and gain some power.

The bottom line is your exhaust will work fine to accomplish your goals. No reason to change it out unless you really want something different.

picco97

Thanks guys I'll try current setup
Anyone know how many psi can I run 93 octane With novi1200 stock long block I made previously 91 Cali pump gas 12.5 psi with NOVI1000 310whp mustang dyno(very low reading) I'm going to try 14.5 psi with 93 octane(will mix 91 with 100 make 93) if possible for safe range

LDfavoriteson

I hit 16.5 psi on 93 octane with a novi1200 stock long block

99SH

Gut feel says you're going to pull a lot of timing to run that boost level safely for such a low octane. Personally I'd stick to the 9-10 PSI range on pump (91) gas.

Habitforming

my kw kit is hitting 16's on 93. Stick header and exhaust, berk hfc

picco97

I tuned 91 octane but End of tune I will use 93 octane so I think should be fine 12.5-14.5 psi

06S2k07Si

My experience here: https://www.s2ki.com/s2000/topic/817...ube-sc-header/