jaxcam02

iTrader: (1)

I bought my LS1 camaro in 2011. Within the first week, I raced some kind of import from a dig. I don't remember exactly what it was but it kept up with me. I was not happy about it. New plugs, removing the K&N filter for a paper one and cleaning the MAF, and new fluids on the stock LS1 changed that. I never experienced something so embarrassing again in the camaro. Now its a full H/C/I can with true duals and I don't loose much to anything anymore.

First thing I would do is go through the plugs, get a tuner to look at your tune and make sure its not some funky handheld crap tune or something.

RPM WS6

iTrader: (3)

^ Always a good idea to cover the basic maintenance items on a new-to-you old car, but the OP seems to be missing about ~140hp based on the experience he posted (the high speed roll runs were pretty telling, since traction shouldn't be an issue at that point). To be missing that kind of power due to a dirty MAF and/or fouled plugs, I would expect some other issues as well (such as noticeable misfires/rough idle/flashing SES, hesitation under part throttle acceleration, etc.)

IMO, the most likely ways for him to be down by that much power, without any other driveability issues at all, would be intake blockage, throttle body not opening fully at WOT, or low fuel pressure at WOT. There could also be issues with transmission slippage under heavy load but, again, if it had gotten that bad then I would expect some other noticeable driveability issues as well.

Or, of course, it could be that the V6 Mustang in question wasn't actually a V6 at all. Or it was modified (boost, N2O or something like this).

Z28tek

Somethin's up with this thread and OP...

5.7stroker

iTrader: (36)

Half those mustang guys that drive stock cars probably don't even know what engine they have. One guy I worked with back in the day showed up with a 99 mustang and I asked him if it was a v8 and he said he wasn't sure. Turned out it was a v6. You'd be surprise at how easy it is to sell someone a car without them even knowing what is under the hood. He saw that it "looked fast" and bought it.

jetech

If it still has a catalytic converter "temporarily" install a test pipe and check the performance. Then just forget to reinstall the cat if you don't live in an exhaust inspection area

RPM WS6

iTrader: (3)

This would not be easy to do with a '99, since the passenger side cat doesn't unbolt on those (you'd have to cut the Y-pipe, or replace the entire Y-pipe, at which point you might as well just consider a header install at the same time). An easier initial way to check for any major blockage would be to determine cat surface temp with an IR gun. A clogged cat(s) is certainly something which would cause power loss, but at this level of power reduction there would likely be other symptoms as well (such as engine unable to reach high rpms or shutting down at WOT, converter(s) visibly glowing red with heat, and a host of other driveability issues).