After the TD04
+500rpm lag on VF24/28
+600rpm lag on VF29
+650~700rpm lag on VF34
+800rpm lag on VF23/30
+900rpm lag on VF22

all on the same 3" exhaust after removing the std TDO4

All the turbo's with P18 exhaust housing & BB has good off boost response (VF28/34), and top end power of the 34 is very impressive , only down 3 odd kw on the 22 and yet heap more down low .

The VF30 starts late and come on fast , it has poor ish off boost response and very strong mid and top end .

The 30/35 & 34 have very good compressor wheels that work very efficiently and run lower intake temps and this is where the good power comes from .

The power on the 23 & 22 come from the open exhaust housing being a P20 , better exhaust flow and scavenging up top and the cost of some low to mid range power .

VF35 has identical internals to the VF30 and it uses divided thrust bearings. However, the exhaust housing is a P15 which sacrifices top end performance compared to the VF28/30/34's P18 exhaust housing.

The gains from the P18 exhaust housing is of better scavenging of the exhaust stroke in the top end , down side is the loss of low rpm torque as it allows fresh charge to exit the exhaust valves on cam over lap , much the same as what bigger cams do.

Summing that lot all up changing from a VF28 to a VF35 will give slightly (if any) more lag, but you will gain mid range power due to the more efficient (and slightly bigger) 6+6 bladed compressor wheel giving a cooler intake charge.

J