I know SC400 has a huge gas tank right behind the back seats.
can i just put an aftermarket 10" subwoofer to replace the oem sub?
will it fit just like that or will i need to do some customization?
plus 200 - 500w amp.
what do you think?
is it possible?

the oem sub is not woking that well since i change the faceplate with an aftermarket.

 

Did you ever get a response or info regarding this? I have a 300 that I'd ilke to replace the stock sub in.

 

Find a sub thats freeair type and doesnt require a lot of depth when mounting. one of the old pioneer free air subs fits nice...

 

I have a Kicker free-air sub in that spot. Most of the people I consulted when planning my music stuff recommended leaving the space empty so that sound could travel better from the trunk to the car. I went against that advise because there is a barrier board between the trunk and the gas tank space that I thought would impede the sound transference. The sc has a well built insulated trunk and decent power is needed to get sound into the car. I wish I had followed the advise or put in a more powerful amp. I have good sound though, not really complaining.
I have the 8 1/2 Free-Air sub in the window
A 10 inch Punch (Rockford Fosgate) sub in the trunk
A Punch amp

Don't forget there is a factory Pioneer amp powering the other speakers.

 

i think the JL Audio IBL4 works as well ( i don't remember if that's the correct model or not )