Can someone explain this to me?

example: headers, will give you more top end, but will loose a little down low. translation: you will lose abit of torque (what gets ya off the line) but will gain some HP

What these parts do is change the power cuve of the engine. There is always a compromise when adding mods but its the balance of mods which compliment each other which give you a good combo. Cam for example will typically loose power in the lower rpm but really "kicks" in at the higher rpm level. That sacrifice will net you more power overall but for a street car its typically better to find parts which will give you better overall power over more of the useable rpm range than peak dyno numbers for short bursts. Think as to why VTEC is really not a pratical performance feature to depend on... unless you tweak the chip.
Kevin

and we all know nothing can touch vtec

Yeah, low end/high end refers to the rpm of the engine. A track only car is using the upper rpms most of the time. A street car (driven responsibly heh heh) will use the lower rpms most of the time.

You kind of have to decide which purpose the car is for and design your mods to fit the purpose.

The high/low theory is referring to to powerband of the motor. In layman's term if a part will give you more upper power but you will lose some down low. Its like when your at WOT throttle and reach 5500 rpms, the car feels like it has no more, this part will make you feel like the car has more past 5500. In the same light, at the bottom rpms (idle - 2000) your car may feel like it has 3.55 gears instead of say 3.73. This is my analogy. The parts can actually be proven on a dyno to lower the hp/tq in the lower rpms and raise them in the upper. The value of a part should be what it does across the rpm band not peak power.

....that wasn't a stupid question. Better than "3.55's, 3.73's, or 4.10's"?

QDRHRSE said:

....that wasn't a stupid question. Better than "3.55's, 3.73's, or 4.10's"?

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why not get one of each?

It is worth noting that our stangs are sort of in middle ground. In the old days, even the carb's jetting sort of limited high end (vs low end drivability). Stangs are in the middle (and a comparison for them is a mod motor vs a 5.0, stock for stock). The 5.0 has more low end but lacks the high RPM lung of the mod motor (generically speaking).

These days, intakes with flappers (let alone variable lift valvetrains) allow one to have wave tuning for low end but also high end (thanks to the flapper's dynamic). Best of all worlds with the latter.

Sicarius428 said:

for a street car its typically better to find parts which will give you better overall power over more of the useable rpm range

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in my personal opinion if your building a car for the street, not street racing per say, but a car thats used for cruising or giving a corvette a run for its money every now and then. i think that low end power is of more value.
because at least in my expierience i dont pull up next to a car and race them into 4th gear at over 100mph verry often.
(unless your the type who sets up street races) plus, me being a 5spd kinda guy, i can down shift and utilize the rpm's as i wish. i can see upper rpm's being more important in an auto, like if you were to get on it, and the tranny didnt down shift to put you in the optimal gear or rpm range. my old 4.10 geared coupe with cam, intake, and other basics, felt faster and pulled away from alot of cars that were faster then mine. dont get me wrong 11's are 11's and 14's are14's but under the right "street" conditions this car could have fooled ya. this kid with a brand new turbo volvo was baffled when i beat him by 4 car lengths in about an 1/8th mile burning out through 1st and 2nd.
then i told him i had a 100shot on a WOT switch.
n2o aside i like low end power!
SORRY FOR THE RANT! i got carried away