No. Each of those long runner tubes (including the length of each runner in the intake base) acts like pipes in an organ or even blowing across the top of a jug. At certain frequencies, the positive-pressure pulses of this resonance line up in timing with the valve opening and help pack more air into the chamber before the valve closes. This is a mild "supercharging" effect that will boost power around 2400rpm (if I recall the numbers correctly). That's a good thing. The bad thing is that at a frequency 50% higher than, the negative-pressure pulses line up with the intake valve openings and reduce the air going in. That's the brick wall I referred to earlier. This tradeoff was worth it on a stock L98, which was designed back when compression ratios were low and combustion was lazy. Nobody (except a few exotics) were making high-revving engines, so GM could get more power under the curve using resonant tuning of the intake. By the time the LT1 came along, GM was running 10.5:1 or more, and they switched to the short-runner LT intake to move the resonance frequency way outside the RPM range of any engine. For the LT1/4, the intake neither boosted nor limited performance.

The problem with flow bench numbers for a resonance-tuned intake like the TPI is that the bench uses constant flow. There is no resonance because there is no intake valve or piston. So you can measure all the improvements in flow that you want with large-tube runners and ported bases, but that intake is still going to kill power above a certain RPM. You can slightly increase that RPM by increase the runner cross-sectional area, but not a lot. You can also play some tricks with cam timing to mitigate the brick wall effect, but that also compromises power and/or efficiency at other parts of the RPM range. The Super Ram was a similar idea but with runners shortened to make it work at more modern RPMs, where power is made. As I recall, it's runners are roughly the same length as an LS1 intake's runners. That makes it a lot better option for those trying to build some power with larger-port heads and bigger cams. They are hard to find these days, but probably a great option for most who want to bump up power on an L98.

With your stock TPI, I do still believe long-tube headers will be a noticeable improvement. They tend to bump mid-range power due to primary tube length and collector volume (getting back to resonant tuning). The improved flow of the gradual bends and larger primaries probably matters little unless/until you change intakes, and maybe even heads and cam. But that just means they will "grow" with your future improvements. I'd say go for it, but be prepared that this is a big job and tying headers to the rest of the exhaust (or redesigning the exhaust) is not a cheap or easy project.

 

You were not kidding when you say it get expensive. I priced out the hedman premium headers and the very high end Borla or other premium cat back systems. It's close to $3.5K without installation which I have to pay someone to perform. Just thinking out loud, but for a couple more grand I could get someone to do an LS engine swap for much more power than the L98. Does this sound silly to you?

 

I give another vote for headers, I did the cheapest headman's that I got a deal on used, restored them, and get a whole exhaust with it to fit, no bigger than 1 5/8ths, did a 3 to 2.5 in reduction from the collector to the rest of the exhaust so I didn't lose low end power and torque. My car is an 85 with stock heads, cam, ect.

 

Thanks NightRunner. I take it that you did all the work yourself. I lack the skills or the equipment needed so I am going to have to pay some local outfit that I trust to do the install. One other question. When you pull the 2 solenoids valves and I associated vacuum and exhaust piping, did you have to reprogram the ECM so as not to get the "check engine light"?

 

If you can find someone to "LS swap" the car for $5.5k, I can almost guarantee the result will be a mess and won't perform well. These swaps are almost never as straightforward as the webernets wants you to believe, and they are extra challenging in a C4 because you need to either adapt the stock transmission to the LS or else find a way to attach the C-beam to another transmission. And you will forever be beholden to whomever did the work if you can't do the job yourself, because nobody else will be able to decipher what they did. IOW, this is a very bad idea. This won't be a popular thing to say, but honestly you would be better off selling this C4 unmodified and then buying a C5. Those aren't that expensive anymore and you can easily pay someone good to do a cam swap, headers, whatever.

If you want to continue down the C4 path, take a look at Hooker Super Competition Headers. They aren't as expensive as the costliest headers, and they work well. Find a good shop that is willing to install them along with a full header-back exhaust (they will probably only be willing to do that if the new exhaust system includes cats). The labor is still not going to be cheap, but at least you'll save a bit on the headers.

 

I've gone from Stock exhaust manifold --- to Heddman Hedders connected to 3" TPIS Y-Pipes and Magnaflow high flow 3" cat Magnaflow (custom work on fitting the Y-Pipe and scalloping the header collector to matchth eangle of the Y pippe), and then standard bolt on 1986 Magnaflow cat backs... it was nice, worked great, sounded great, but it wasn't a true bolt on... then switched to Exotic Muscle headers and extension pipes (was much nicer and probably easier)... then to American Racing stainless headers with the new engine, that's the best quality by far and bolt on back to the axle if you can put up with their often long lead times to order. These will last a lot longer, will not rust inside, and runs cooler than steel, makes more power with 383 or higher performance setup than stock, looks great too. $2200 shipped.

https://www.summitracing.com/search/...cing%20headers

Make sure you specify "yes" or "no" to emissions bungs on the primaries, I said "no" to that so it's clean and I'm not running any air pump or egr... but they don't seem to have a different part number so make sure it's clarified somewhere in the ordering process.