Yup, will make it accelerate faster, stop faster, handle better.

Its all about the power to weight ratio, you might have no power, but if u got no weight it wont matter so much!

Under carpet sound deadening is pretty heavy.

Most heavy thing (compared to aftermarket ones) is front seats, bigtime, massivley heavy mate compared to fixed back fibreglass bucket seats, over 7 stone each on a cossie if i remember right!

Even small things add up, so remove everything.

On my 3door i removed carpet, roof lining, door cards, seats, seatbelts, stereo, sound deadening behind dash, fan, all plastic interior trim, sun visors, basicly everything, even all wiring you dont need anymore.

Cheapest extra performance you can get