4-5 inch high sensitivity subwoofer

I am looking to upgrade my portabal boombox that i have made, it currently has 2 4" 15w subwoofers in, although they do have a low power rating they do add to the sound, but the only reason why they are in is because they were left over from something in the house i did just find them and use them, so the amplifier that i have is a lepai 168ha, this can output 68w to the subs and 40×2 to the mid to high range frequesnies, can anyone find me a pair of 4-5 inch drivers which are made for a relitivly small enclousure (18"×7"×6" with nothing in) and are under 200w as i will not be able to drive that much and i will be wasting money as i can never get them to their full volume, if there is a single sub which is just too good to be true then i may settle for a max 7" driver but only one of them

Many thanks to anyone who can help me
 
Yeah, i know its a big ask but the ones that i have in now are barely on 10% of the amps output, with the input being on max from a smartphone so not the lousest input, so i was looking for something that can handle higer power even if it does only "double" the volume if it takes up 100%
 
I am looking to upgrade my portabal boombox that i have made, it currently has 2 4" 15w subwoofers in, although they do have a low power rating they do add to the sound, but the only reason why they are in is because they were left over from something in the house i did just find them and use them, so the amplifier that i have is a lepai 168ha, this can output 68w to the subs and 40×2 to the mid to high range frequesnies, can anyone find me a pair of 4-5 inch drivers which are made for a relitivly small enclousure (18"×7"×6" with nothing in)... may settle for a max 7" driver
Hi,
For 12L/0.44cf enclosures use 7" Dayton Audio DA175-8 or Wavecor SW182BD01. Another interesting is Peerless SBS-160F35CP01-04.
Dayton Audio DA175-8 7" Aluminum Cone Woofer
SUBWOOFER WAVECOR SW182BD01
https://www.hifisound.de/Peerless-SBS-160F35CP01-04.html