diff --git a/lib/Slic3r/GCode.pm b/lib/Slic3r/GCode.pm
index 008ab4669..969991f93 100644
--- a/lib/Slic3r/GCode.pm
+++ b/lib/Slic3r/GCode.pm
@@ -8,6 +8,7 @@ use Slic3r::Geometry::Clipper qw(union_ex);
 use Slic3r::Surface ':types';
 
 has 'config'             => (is => 'ro', required => 1);
+has 'extra_variables'    => (is => 'rw', default => sub {{}});
 has 'extruders'          => (is => 'ro', required => 1);
 has 'multiple_extruders' => (is => 'lazy');
 has 'standby_points'     => (is => 'rw');
@@ -549,7 +550,8 @@ sub unretract {
             $gcode .= "G11 ; unretract\n";
         } elsif ($self->config->extrusion_axis) {
             # use G1 instead of G0 because G0 will blend the restart with the previous travel move
-            $gcode .= sprintf "G1 E%.5f F%.3f",
+            $gcode .= sprintf "G1 %s%.5f F%.3f",
+                $self->config->extrusion_axis,
                 $self->extruder->extrude($to_unretract),
                 $self->extruder->retract_speed_mm_min;
             $gcode .= " ; compensate retraction" if $self->config->gcode_comments;
@@ -644,7 +646,7 @@ sub set_extruder {
     
     # append custom toolchange G-code
     if (defined $self->extruder && $self->config->toolchange_gcode) {
-        $gcode .= sprintf "%s\n", $self->print->replace_variables($self->config->toolchange_gcode, {
+        $gcode .= sprintf "%s\n", $self->replace_variables($self->config->toolchange_gcode, {
             previous_extruder   => $self->extruder->id,
             next_extruder       => $extruder->id,
         });
@@ -743,4 +745,9 @@ sub set_bed_temperature {
     return $gcode;
 }
 
+sub replace_variables {
+    my ($self, $string, $extra) = @_;
+    return $self->config->replace_options($string, { %{$self->extra_variables}, %{ $extra || {} } });
+}
+
 1;
diff --git a/lib/Slic3r/GCode/Layer.pm b/lib/Slic3r/GCode/Layer.pm
index a08ec2d98..0a24dfcc6 100644
--- a/lib/Slic3r/GCode/Layer.pm
+++ b/lib/Slic3r/GCode/Layer.pm
@@ -66,7 +66,7 @@ sub process_layer {
     
     # set new layer - this will change Z and force a retraction if retract_layer_change is enabled
     $gcode .= $self->gcodegen->change_layer($layer);
-    $gcode .= $self->print->replace_variables($Slic3r::Config->layer_gcode, {
+    $gcode .= $self->gcodegen->replace_variables($Slic3r::Config->layer_gcode, {
         layer_num => $self->gcodegen->layer->id,
     }) . "\n" if $Slic3r::Config->layer_gcode;
     
diff --git a/lib/Slic3r/GUI/Plater.pm b/lib/Slic3r/GUI/Plater.pm
index 4ec4847d3..ee90576d9 100644
--- a/lib/Slic3r/GUI/Plater.pm
+++ b/lib/Slic3r/GUI/Plater.pm
@@ -594,8 +594,10 @@ sub split_object {
             input_file_object_id    => undef,
             model                   => $new_model,
             model_object_idx        => $#{$new_model->objects},
-            instances               => [ map $bb->min_point, 1..$current_copies_num ],
+            mesh_stats              => $mesh->stats,  # so that we can free model
+            instances               => [ map $bb->min_point->pp, 1..$current_copies_num ],
         );
+        
         push @{ $self->{objects} }, $object;
         $self->object_loaded($#{ $self->{objects} }, no_arrange => 1);
     }
@@ -1289,7 +1291,7 @@ has 'thumbnail_scaling_factor' => (is => 'rw', trigger => \&_transform_thumbnail
 has 'config'                => (is => 'rw', default => sub { Slic3r::Config->new });
 has 'layer_height_ranges'   => (is => 'rw', default => sub { [] }); # [ z_min, z_max, layer_height ]
 has 'material_mapping'      => (is => 'rw', default => sub { {} }); # { material_id => extruder_idx }
-has 'mesh_stats'            => (is => 'rw');
+has 'mesh_stats'            => (is => 'ro', required => 1);
 
 # statistics
 has 'facets'                => (is => 'rw');
diff --git a/lib/Slic3r/Model.pm b/lib/Slic3r/Model.pm
index e6529ecdc..46e74da4a 100644
--- a/lib/Slic3r/Model.pm
+++ b/lib/Slic3r/Model.pm
@@ -308,7 +308,7 @@ use Storable qw(dclone);
 has 'input_file' => (is => 'rw');
 has 'model'     => (is => 'ro', weak_ref => 1, required => 1);
 has 'volumes'   => (is => 'ro', default => sub { [] });
-has 'instances' => (is => 'rw');
+has 'instances' => (is => 'rw'); # in unscaled coordinates
 has 'config'    => (is => 'rw', default => sub { Slic3r::Config->new });
 has 'layer_height_ranges' => (is => 'rw', default => sub { [] }); # [ z_min, z_max, layer_height ]
 has 'material_mapping'      => (is => 'rw', default => sub { {} }); # { material_id => extruder_idx }
diff --git a/lib/Slic3r/Print.pm b/lib/Slic3r/Print.pm
index 8e7b5d56a..e79585b1a 100644
--- a/lib/Slic3r/Print.pm
+++ b/lib/Slic3r/Print.pm
@@ -721,6 +721,7 @@ sub write_gcode {
     # set up our extruder object
     my $gcodegen = Slic3r::GCode->new(
         config              => $self->config,
+        extra_variables     => $self->extra_variables,
         extruders           => $self->extruders,    # we should only pass the *used* extruders (but maintain the Tx indices right!)
         layer_count         => $self->layer_count,
     );
@@ -744,7 +745,7 @@ sub write_gcode {
         }
     };
     $print_first_layer_temperature->(0);
-    printf $fh "%s\n", $self->replace_variables($Slic3r::Config->start_gcode);
+    printf $fh "%s\n", $gcodegen->replace_variables($Slic3r::Config->start_gcode);
     $print_first_layer_temperature->(1);
     
     # set other general things
@@ -897,7 +898,7 @@ sub write_gcode {
     # write end commands to file
     print $fh $gcodegen->retract if $gcodegen->extruder;  # empty prints don't even set an extruder
     print $fh $gcodegen->set_fan(0);
-    printf $fh "%s\n", $self->replace_variables($Slic3r::Config->end_gcode);
+    printf $fh "%s\n", $gcodegen->replace_variables($Slic3r::Config->end_gcode);
     
     foreach my $extruder (@{$self->extruders}) {
         printf $fh "; filament used = %.1fmm (%.1fcm3)\n",
@@ -944,12 +945,7 @@ sub expanded_output_filepath {
         # path is a full path to a file so we use it as it is
     }
     
-    return $self->replace_variables($path, $extra_variables);
-}
-
-sub replace_variables {
-    my ($self, $string, $extra) = @_;
-    return $self->config->replace_options($string, { %{$self->extra_variables}, %{ $extra || {} } });
+    return $self->config->replace_options($path, { %{$self->extra_variables}, %$extra_variables });
 }
 
 # given the path to a file, this function returns its filename with and without extension
diff --git a/t/gcode.t b/t/gcode.t
index bb51698d4..f8ee4158c 100644
--- a/t/gcode.t
+++ b/t/gcode.t
@@ -46,8 +46,13 @@ use Slic3r::Test;
     my $config = Slic3r::Config->new_from_defaults;
     $config->set('complete_objects', 1);
     $config->set('duplicate', 2);
+    $config->set('extrusion_axis', 'A');
     my $print = Slic3r::Test::init_print('20mm_cube', config => $config);
-    ok Slic3r::Test::gcode($print), "complete_objects";
+    ok my $gcode = Slic3r::Test::gcode($print), "complete_objects";
+    Slic3r::GCode::Reader->new->parse($gcode, sub {
+        my ($self, $cmd, $args, $info) = @_;
+        fail 'unexpected E argument' if defined $args->{E};
+    });
 }
 
 __END__
diff --git a/t/multi.t b/t/multi.t
index 0071363d9..855461791 100644
--- a/t/multi.t
+++ b/t/multi.t
@@ -21,6 +21,7 @@ use Slic3r::Test;
     $config->set('extruder_offset', [ [0,0], [20,0], [0,20] ]);
     $config->set('temperature', [200, 180, 170]);
     $config->set('first_layer_temperature', [206, 186, 166]);
+    $config->set('toolchange_gcode', ';toolchange');  # test that it doesn't crash when this is supplied
     
     my $print = Slic3r::Test::init_print('20mm_cube', config => $config);
     
diff --git a/xs/src/TriangleMesh.cpp b/xs/src/TriangleMesh.cpp
index b08e7cb5e..b59d67ca9 100644
--- a/xs/src/TriangleMesh.cpp
+++ b/xs/src/TriangleMesh.cpp
@@ -547,8 +547,11 @@ TriangleMesh::split() const
         mesh->stl.stats.original_num_facets = mesh->stl.stats.number_of_facets;
         stl_allocate(&mesh->stl);
         
+        int first = 1;
         for (std::deque<int>::const_iterator facet = facets.begin(); facet != facets.end(); facet++) {
             mesh->stl.facet_start[facet - facets.begin()] = this->stl.facet_start[*facet];
+            stl_facet_stats(&mesh->stl, this->stl.facet_start[*facet], first);
+            first = 0;
         }
     }
     
diff --git a/xs/src/admesh/stl.h b/xs/src/admesh/stl.h
index 332a5bf2f..ac4143858 100644
--- a/xs/src/admesh/stl.h
+++ b/xs/src/admesh/stl.h
@@ -178,6 +178,6 @@ extern void stl_initialize(stl_file *stl);
 static void stl_count_facets(stl_file *stl, char *file);
 extern void stl_allocate(stl_file *stl);
 static void stl_read(stl_file *stl, int first_facet, int first);
-static void stl_facet_stats(stl_file *stl, stl_facet facet, int first);
+extern void stl_facet_stats(stl_file *stl, stl_facet facet, int first);
 extern void stl_reallocate(stl_file *stl);
 extern void stl_get_size(stl_file *stl);
diff --git a/xs/t/01_trianglemesh.t b/xs/t/01_trianglemesh.t
index c9eb44de4..3fc4bd0f0 100644
--- a/xs/t/01_trianglemesh.t
+++ b/xs/t/01_trianglemesh.t
@@ -4,7 +4,7 @@ use strict;
 use warnings;
 
 use Slic3r::XS;
-use Test::More tests => 51;
+use Test::More tests => 52;
 
 is Slic3r::TriangleMesh::hello_world(), 'Hello world!',
     'hello world';
@@ -59,6 +59,7 @@ my $cube = {
         my $meshes = $m->split;
         is scalar(@$meshes), 1, 'split';
         isa_ok $meshes->[0], 'Slic3r::TriangleMesh', 'split';
+        is_deeply $m->bb3, $meshes->[0]->bb3, 'split populates stats';
     }
     
     my $m2 = Slic3r::TriangleMesh->new;