The bigger Mitsi TD06-20g is good for around 485hp (650cfm) as opposed to the 375hp(505cfm) of the standard 16g6 compressor wheel.
The 20g compressor wheel is effectively one size larger than the 16g6 although it's overall diameter is the same at 68mm.
The TD06 has a larger turbine wheel (65mm dia) than the TD05 (56mm dia.) fitted as standard on all evo's.
The increased rotational inertia (mainly from the larger turbine wheel) will increase spin up lag. A tubular exhaust manifold may offset this slightly but only if is well designed with the correct length runners.
The standard evo turbo installation (5 onwards) is very effective at reducing lag with it's twin entry turbine - especially in titanium aluminide turbine wheel RS form with it's reduced inertia.
BTW - it's a shame that the TME GSR has a smaller 15G compressor wheel - why!!!???
The biggest pain in the arse is that Mitsubishi reversed the rotating direction compared to all their previous turbos and to pretty much all the existing turbos from other manufacturers.
(If anyone knows of another make of anticlockwise spinning turbo then please let me know).
This means that there are no compressor wheel upgrades for the td05hr-16g6 turbo. (the r indicates the reverse spin). It is a big shame as a 20g compressor wheel in a td06 compressor housing fitted to a td05 centre and exhaust would be the perfect upgrade for a 450hp evo.
Fitting a larger turbo will always increase lag (unless antilag is used) to some extent. On a race track you will normally be over 4000 rpm at all times so this shouldn't be much of a problem. The off boost performance of evo's is pretty good anyway with their 8.8:1 compression ratio.
So what are the options
Standard Mitsubishi td05hr-16g6 10.5 375hp
16g6 compressor wheel ( 48.0/68.0mm) (inducer dia/exducer dia.)
16g6 Comp hsg
td05h turbine (55.8mm/49.0mm) (inducer dia/exducer dia.)
Twin entry turbine housing 10.5cm2.
Greddy - td06-20g. 485hp
20g compressor wheel (52.6mm/68.0mm)
20g Comp hsg
td06h turbine (65.0mm/55.2mm)
Turbine housing ?cm2.
HKS GT Ball Bearing Series – based on Garrett parts
GT2835R – 420hp rating
56 trim compressor wheel (53.1mm/71.1mm)
.50AR Comp hsg 100mm intake / 50mm outlet
90 trim T25 turbine (56.5mm/53.6mm)
Turbine housing 0.61 8cm2, 0.73 10 cm2, 0.87 12 cm2, 1.01 14 cm2, 1.12 16 cm2,
GT3037
48 trim compressor wheel (52.8mm/76.2mm) – 420hp rating (Garrett T04S 48)
52 trim compressor wheel (55.0mm/76.2mm) – 440hp rating (Garrett T04S 52)
56 trim compressor wheel (57.0mm/76.2mm) – 470hp rating (Garrett T04S 60)
.60AR Comp hsg 70mm intake / 50mm outlet
84 trim T3 turbine (60.0mm/55.0mm)
Turbine housing 0.61 8cm2, 0.73 10 cm2, 0.87 12 cm2, 1.01 14 cm2, 1.12 16 cm2,
GT3037R
52 trim compressor wheel (55.0mm/76.2mm) – 450hp rating (Garrett T04S 52)
56 trim compressor wheel (57.0mm/76.2mm) – 480hp rating (Garrett T04S 56)
.60AR Comp hsg 100mm intake / 50mm outlet
84 trim T3 turbine (60.0mm/55.0mm)
Turbine housing 0.61 8cm2, 0.73 10 cm2, 0.87 12 cm2, 1.01 14 cm2, 1.12 16 cm2,
GT3040– 500hp rating
50 trim compressor wheel (58.0mm/82.0mm) (Garrett T04S GT40???)
.70AR Comp hsg 100mm intake / 60mm outlet
84 trim T3 turbine (60.0mm/55.0mm)
Turbine housing 0.61 8cm2, 0.73 10 cm2, 0.87 12 cm2, 1.01 14 cm2, 1.12 16 cm2,
Garrett Ballistic Concepts Ball Bearing Turbo
GT25 – 450hp rating
48 trim T04S compressor wheel (53.1mm/71.1mm)
.70AR Comp hsg
76 trim turbine (53.8mm/47.0mm)
Turbine housing 0.86 (12 cm2?) (Smaller 0.64 trim housing only rated for 350hp)
GT30 – 500hp rating
56 trim T04S compressor wheel (57.1mm/76.2mm)
.70AR Comp hsg
84 trim turbine (59.9mm/54.9mm)
Turbine housing 0.63, 0.82, 1.06
(Smaller AR housing will give less lag but will restrict exhaust gas flow at high rpms leading to higher manifold temperature)
Turbonetics Ceramic Ball Bearing – I have not heard many good stories about turbonetics.
Blitz – KKK turbos ???
IHI - ???
My recommendation would be an HKS GT3037R 56 trim or Garrett GT30.
Both have ball bearing centre section to reduce lag and increase reliability. Use a small to medium exhaust housing - say 0.8 AR for less lag.