I went through a "power" stage when I had my 2.0TS, I wanted to squeeze everything out of it I could on a limited budget.
I had the car Dyno'd at TurboPacs in Durham and was kicking out a healthy 145bhp at the flywheel which wasn't bad for a ten year old car and completely standard.
New sparks, oil and filter change, coolant and gearbox oil change... Followed by an Apiro dual cone filter that I fitted at the top of the existing airbox(fits perfectly where the lid used to be)
Next, I removed the resonator on the TS that you refer too Gary and fitting a V6 trumpet to the old airbox. That must have saved about 5KG in itself!
I also changed the exhuast centre and rear for CSC and went back to the dyno... 156 bhp at the flywheel! I got all those escaped horses back
Wish I had kept the print outs now, gave them to the new owner with all the car records and bills when I got rid of it
Personally I think a good service versus mods worked out 50/50 in the gains I got back..
i'll never underestimate the value of a damn good service ever again
But it is worth sorting out the induction side of any alfa engine, they seem to respond well to it plus the added benefit of finally sorting the Achilles heal to all Alfa's, the MAF contamination/ Airbox lid and split rubber induction pipe all in one go