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I've been watching this thread for a while now to see what people would say and it's been interesting. As you've found out you've losted some bottom end which was to be expected by lowering the back pressure of the exhaust system, but lowering it more you will loose even more by pushing the peak torque curve even highter, by the way where/what rpm does it "feel' about the same as it was before, 3000, 4000, etc.? As Daniel pointed out our small under 100 cubic inch engine just don't have that much grunt anyway to start with, so why take it away.
When I put my header on I wasn't expecting much and was pleasently surprised when it produced an increase starting at 3K which is just off idle anyway. It now has a pretty flat torque curve starting a 3K and goes almost all the way to redline which is fine for normal driving (you don't drive in VTEC all the time anyway). One plus was when passing a car on the freeway, I don't have to down-shift into 4th anymore, just hit the gas and go. I would estimate it at 5-7 hp max at the flywheel, with a 2-3 hp gain at the wheels. So as you can see the design of the header does make a difference as to where the power/torque is placed.
As to your loss in torque, you can make it back up and more so by installing a Skunk2 intake manifold (a very well thought out design if I do say so myself), the runners are much longer (for more bottom end torque) then the stock manifold to help in this area (for an example, I rode in a members car that has one on his and I was very impressed with the response and power that gave it, now I think he was using DC Sports as a header with this set-up, which runs pretty small pipe (1 1/2 inch in size, and a 4-2-1 design) with a 60 or 62mm throttle bore, which in my mind was a bit of over-kill, (much bigger then what I would run unless I was going all out with the motor). The Skunk2 seem to start giving more power from around 3k up, it's definitely a street manifold giving you the juice where you need it most.
Anyway I hope this gives you some "food for thought" on it and hope your enjoying the new header, stainless steel rocks!!!
Geo
President
Team Sol of Washington
http://img12.exs.cx/img12/9927/car30.jpg
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I forgot to add on my other post: Did you re-set the computer after you put the header on? It will re-program it's self, but it just takes a bit more time for it to do it by it's self.
Geo
President
Team Sol of Washington
http://img12.exs.cx/img12/9927/car30.jpg
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good info and good to know. As far as where i feel the extra power and extra loss..i'm not too quite sure. Still havn't gotten that chance to romp on it. As far as intake manifolds go, there's so much debate as to whcih one is better, i hear very good things about the skunk2 intake mani and then i hear some small issues with them. I believe one of them might have been a clearance issue with it hitting the firewall but i cant completely recall. I hear nothing but good things about edelbrock(sp) though, and i believe there was one more brand name that did better than edelbrock on a dyno proven test result but i cant recall that either. I'll search honda-tech later for it. Also, i'm not too quite sure if i wanna drop $200-$300 for an intake manny for my d16, i just dont imagine seeing enough gains for it to be worth the time and effort. I figure, they cost as much as the ones for DOHC motors so i should just wait until i get one and then get a mroe agressive intake manny. I came across a VERY interesting thread last night on this d series website/forum. It had a list of things to do to make your SOHC d16z6/y8 get up to about 160whp. i'll post links later on tonight or tomorrow when i get the chance.
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