Do they help significantly to reduce turbo lag?

 

if anything they will increase lag, but if you want to make SERIOUS WHP up top, cams are a MUST, they keep the valves open longer, more air, more fuel, more power...

 

They do not just help on the top end. My HKS 264/272e combo spools much quicker than stock, makes more power off boost and has a much stronger mid-range as well as the afore mentioned top end benefits. Definitely when well tuned, cams and cam gears will reduce lag

 

Only if your car was completely tuned like *** prior to the cam's. The whole reason cams make more power is the move your peak VE higher in the rev range with increased lift, and most importantly, increased overlap...which, of course, causes a loss of dynamic compression at lower RPM. SDo unless your EVO is VTEC equipped, tune for tune, cams tend to add lag. My straight 272's were about 200 RPM additional lag.