lack of punch / tight bass from subwoofer

Hey,
i got a 08 Impreza and i installed a new subwoofer and amplifier. I had an Infinity basslink before and it was playing very well until it roll over in my trunk and stopped playing. So i had a deal on a new set. Everything run on same wiring and HU as before. It seem like the sub doesn't kick at all, i mean i can hear sound coming from it but there no punch from it. I even tried to turn gain at 80% sub.w level at 8 (Max) on HU and volume at 70% still nothing. I got more punch from the factory speaker in the car than the sub.

Crossover on the HU is at 120Hz and around the same on the AMP. The sub is used and maybe he is blow ?


Amp: Clarion APX201.2 230RMS at 4OHMS bridged (New)
Sub: TS-SWX251 Preloaded Shallow 200W RMS at 4 ohms in sealed box (used)
HU: JVC KW-800BT (New)

make sure the amps crossover is set to LPF( low pass filter). if the amp is set on HPF then you are only hearing higher frequencies of bass and thus you wont get any good low bass or punch. your infinity basslink is a strictly bass only system so it probably didnt have a switch for a HPF/LPF setting. your new amp is a multi channel amp that can be used for highs or bass and so it should have a HPF/LPF switch

Update

LPF Switch was set correctly. I switched the polarity on the subwoofer and boom bass appear. I think the polarity inside the box are reversed.