Quote:
Originally Posted by Zsteve
One reason I would think the FI makes a little more than others might be the fact that it really has little to no turns which cause restriction. That would be the only way I can see it making more, and maybe only 2 - 4 more IMO.
|
You're also forgetting the fact that its long tube design eliminates the catalytic converters, freeing up HP/TQ there also.
The reason why most headers on newer cars (of normal design, not long tube), is that efficiency can no longer be found in designing normal equal length tubes. Factory OEM designs are so well made that it is difficult to notice any real difference in power by upgrading headers. Nowadays headers are mainly designed for tuning the powerband, which is why other headers for the VQ37 have really only shifted the power band one way or another, and power gains have been negligible.
What makes this so different is twofold: it eliminates what is arguably the most restrictive area of the exhaust- the cats, and the longer tubes down to the collector located downstream probably even out the airflow a little more. Those two factors, and the one you mentioned about less bends in the header design, probably account for most of the power gains.
Let's not forget that semtex's review is based off of high-flow cats and a stillen header vs. FI LTH and he already got a noticeable power gain. I'd also like to point out that he's running the Stillen CBE.
I'm curious to see what the FI LTH would do on a car with bone stock exhaust mods to quell any debate over FI LTH w/ Stillen CBE vs. FI LTH w/ FI CBE power gains. I don't really think it matters which CBE you pair with these headers, it will definitely make a difference with either provided the exhaust diameter pairs with NA builds.