mines made a lot of difference to the sound :S before you couldnt hear the car at all really not sounds a bit meatier. Tbh ive probs lost bhp because of it but am well happy just because of how it sounds.
obviously exhaust will make a much bigger change to the noise but are much more expensive.
My induction kit only cost £14.99 from ebay (topgearshop was the seller i think) but the same ones seem to be £50+ from online shops. Its wolfrace

quiet

but does the job tbh
Deffo worth it because of pure cheapness and new noise