What kind of amp is your friend running that peaks out at 2400watts. Reason I ask is because certain brands will be significantly lower than the number the slap on the label.
Take your peak number (in this case 2400) multiply it by .70 (if it is a cheap model, like pyramid, legacy, jensen, etc) multiply it again .70) the number you and up with will be around 1250watts, this is what your amp should be running RMS, so find a set of subs that handles close to 1200watts RMS,
Your impedance is not extremely important to match. However, it is not recommended to go below the minimum impedance that the amplifier will safely operate at. Since you have a 4ohm sub, and the amp produces max power at 2ohms, at 4ohms you are only going to have approximately 1/2 as much power, so all of a sudden that 1250 you had available is now around 625 RMS. However, if the sub is 1000watts PEAK then it is only handles approx 700watts RMS so it might be efficiently run by the amp.
Take your peak number (in this case 2400) multiply it by .70 (if it is a cheap model, like pyramid, legacy, jensen, etc) multiply it again .70) the number you and up with will be around 1250watts, this is what your amp should be running RMS, so find a set of subs that handles close to 1200watts RMS,
Your impedance is not extremely important to match. However, it is not recommended to go below the minimum impedance that the amplifier will safely operate at. Since you have a 4ohm sub, and the amp produces max power at 2ohms, at 4ohms you are only going to have approximately 1/2 as much power, so all of a sudden that 1250 you had available is now around 625 RMS. However, if the sub is 1000watts PEAK then it is only handles approx 700watts RMS so it might be efficiently run by the amp.
