K&N filter re-located in front of battery with cold air feeds from under car got the following results:
Start Speed   0.0mph
 mph       s   g   ft      hp 
 10.0    0.88 0.53     6   35
 20.0    1.70 0.56    24   74
 30.0    2.49 0.59    53  120
 40.0    3.38 0.43    99  121
 50.0    4.92 0.35   199  126
 60.0    6.31 0.31   312  142
 70.0    8.43 0.23   514  134
Pk Power:  69.2mph   8.26s   497ft   151hp
  Peak G:  33.2mph   2.72s    64ft  0.61g
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Start Speed   0.0mph
 mph       s   g   ft      hp 
 10.0    0.92 0.51     6   34
 20.0    1.78 0.53    25   71
 30.0    2.60 0.55    55  112
 40.0    3.43 0.48    98  131
 50.0    4.90 0.34   194  123
 60.0    6.20 0.33   299  149
Pk Power:  61.1mph   6.35s   313ft   154hp
  Peak G:  36.6mph   3.11s    80ft  0.59g
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I then moved it, and attached it to the elbow coming off the throttle body, and this happened:
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Start Speed   0.0mph
 mph       s   g   ft      hp 
 10.0    1.01 0.56     6   36
 20.0    1.83 0.55    24   73
 30.0    2.67 0.51    55  103
 40.0    3.82 0.16   116   50
 50.0    5.28 0.31   211  115
 60.0    6.77 0.28   332  128
Pk Power:  62.0mph   7.07s   359ft   141hp
  Peak G:  12.6mph   1.21s     9ft  0.58g
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Start Speed   0.0mph
 mph       s   g   ft      hp 
 10.0    0.98 0.58     6   38
 20.0    1.78 0.59    23   78
 30.0    2.76 0.48    59   99
 40.0    4.05 0.28   127   80
 50.0    5.38 0.33   216  121
 60.0    6.86 0.28   335  131
Pk Power:  60.4mph   6.92s   341ft   137hp
  Peak G:  21.1mph   1.86s    25ft  0.59g
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....oh dear. If you do put one on, make sure you buy some hosing with it and locate it away from the heat of the engine bay. Ive switched to using a Pipercross Viper now, but the relocated K&N worked as well and sounded better.
Although, as Neil says, for pure performance, a panel filter and an RSport ECU are the best bet.