6 exhaust ? Options

[scotty b]

Over the years I have seen many on here use stock 6 exhaust headers on 2.7 - 3.2 engines. Seems to me they are a bit puny ( not enough i.d. to flow well ) on anything over a mild 2.4 (IMG:style_emoticons/default/confused24.gif) Am I right on this ? Assuming so what options are there for the larger displacement / horsepower engines ?

[Larry.Hubby]

I suppose it depends on what part of the rev range you want to optimize. You are correct that the stock 914-6 heater boxes are on the small side (1 3/8" dia. primaries), even for the stock 2.0 liter engine size, IF you're talking about race conditions and the 5000-6500 rpm part of the power curve. I had 1 3/4" headers on my 3.0 conversion for years, and can testify that it gave great results up near the redline, but was surprisingly gutless down where I used it 99+% of the time (2500-4500 rpm). As soon as I bolted on the stock parts, I noticed drive-ability and apparent power improved dramatically under daily driving conditions. I've also heard from others with sixes and six conversions that the stock exhaust parts are not only OK for engines up to about 3.2, but seem actually much better most of the time because they improve the mid-range power. No question that, if you got into a top end contest in a car like mine with someone in a similar car but larger diameter headers, you'd be at a disadvantage. What most people tend to overlook, however, is that you give up quite a lot in terms of mid-range power to get that top-end performance when you switch to larger headers, and you use the former much more often than the latter.