diff --git a/res/layout/preference_importance_slider.xml b/res/layout/preference_importance_slider.xml
index 737254be11b..d7d04b4a8b5 100644
--- a/res/layout/preference_importance_slider.xml
+++ b/res/layout/preference_importance_slider.xml
@@ -55,23 +55,26 @@
 
             <ImageView
                     android:id="@+id/low_importance"
-                    android:src="@android:drawable/ic_menu_close_clear_cancel"
+                    android:src="@*android:drawable/ic_notification_block"
                     android:layout_gravity="center_vertical|start"
                     android:layout_width="24dp"
                     android:layout_height="24dp" />
 
             <SeekBar
                     android:id="@*android:id/seekbar"
-                    android:layout_marginStart="24dp"
-                    android:layout_marginEnd="24dp"
+                    android:layout_marginStart="56dp"
+                    android:layout_marginEnd="56dp"
                     android:layout_gravity="center_vertical"
                     android:layout_width="match_parent"
                     android:layout_height="wrap_content"
-                    android:focusable="true"/>
+                    android:focusable="true"
+                    android:background="#00ffffff"
+                    style="@android:style/Widget.Material.SeekBar.Discrete"
+                    android:tickMarkTint="@android:color/black"/>
 
             <ImageView
                     android:id="@+id/max_importance"
-                    android:src="@android:drawable/ic_popup_reminder"
+                    android:src="@*android:drawable/ic_notification_alert"
                     android:layout_gravity="center_vertical|end"
                     android:layout_width="24dp"
                     android:layout_height="24dp" />
diff --git a/src/com/android/settings/Utils.java b/src/com/android/settings/Utils.java
index 709277b8bd8..4afa1d96fa3 100644
--- a/src/com/android/settings/Utils.java
+++ b/src/com/android/settings/Utils.java
@@ -34,11 +34,8 @@ import android.content.IntentFilter;
 import android.content.pm.ApplicationInfo;
 import android.content.pm.IPackageManager;
 import android.content.pm.IntentFilterVerificationInfo;
-import android.content.pm.PackageInfo;
 import android.content.pm.PackageManager;
-import android.content.pm.PackageManager.NameNotFoundException;
 import android.content.pm.ResolveInfo;
-import android.content.pm.Signature;
 import android.content.pm.UserInfo;
 import android.content.res.Resources;
 import android.content.res.TypedArray;
@@ -707,35 +704,6 @@ public final class Utils extends com.android.settingslib.Utils {
         return tm.getSimCount() > 1;
     }
 
-    /**
-     * Determine whether a package is a "system package", in which case certain things (like
-     * disabling notifications or disabling the package altogether) should be disallowed.
-     */
-    public static boolean isSystemPackage(PackageManager pm, PackageInfo pkg) {
-        if (sSystemSignature == null) {
-            sSystemSignature = new Signature[]{ getSystemSignature(pm) };
-        }
-        return sSystemSignature[0] != null && sSystemSignature[0].equals(getFirstSignature(pkg));
-    }
-
-    private static Signature[] sSystemSignature;
-
-    private static Signature getFirstSignature(PackageInfo pkg) {
-        if (pkg != null && pkg.signatures != null && pkg.signatures.length > 0) {
-            return pkg.signatures[0];
-        }
-        return null;
-    }
-
-    private static Signature getSystemSignature(PackageManager pm) {
-        try {
-            final PackageInfo sys = pm.getPackageInfo("android", PackageManager.GET_SIGNATURES);
-            return getFirstSignature(sys);
-        } catch (NameNotFoundException e) {
-        }
-        return null;
-    }
-
     /**
      * Returns elapsed time for the given millis, in the following format:
      * 2d 5h 40m 29s
diff --git a/src/com/android/settings/notification/AppNotificationSettings.java b/src/com/android/settings/notification/AppNotificationSettings.java
index 2ee2b811089..9add4eba90d 100644
--- a/src/com/android/settings/notification/AppNotificationSettings.java
+++ b/src/com/android/settings/notification/AppNotificationSettings.java
@@ -70,7 +70,6 @@ public class AppNotificationSettings extends SettingsPreferenceFragment {
     private PreferenceCategory mCategories;
     private AppRow mAppRow;
     private boolean mCreated;
-    private boolean mIsSystemPackage;
     private int mUid;
 
     @Override
@@ -126,12 +125,10 @@ public class AppNotificationSettings extends SettingsPreferenceFragment {
             toastAndFinish();
             return;
         }
-        mIsSystemPackage = Utils.isSystemPackage(pm, info);
-
         addPreferencesFromResource(R.xml.app_notification_settings);
         mBlock = (SwitchPreference) findPreference(KEY_BLOCK);
 
-        mAppRow = mBackend.loadAppRow(pm, info.applicationInfo);
+        mAppRow = mBackend.loadAppRow(pm, info);
 
         // load settings intent
         ArrayMap<String, AppRow> rows = new ArrayMap<String, AppRow>();
@@ -160,7 +157,7 @@ public class AppNotificationSettings extends SettingsPreferenceFragment {
         }
 
         mBlock.setChecked(mAppRow.banned);
-        updateDependents(mAppRow.banned);
+        updateDependents(mAppRow.systemApp, mAppRow.banned);
 
         mBlock.setOnPreferenceChangeListener(new OnPreferenceChangeListener() {
             @Override
@@ -171,7 +168,7 @@ public class AppNotificationSettings extends SettingsPreferenceFragment {
                 }
                 final boolean success =  mBackend.setNotificationsBanned(pkg, mUid, banned);
                 if (success) {
-                    updateDependents(banned);
+                    updateDependents(mAppRow.systemApp, banned);
                 }
                 return success;
             }
@@ -200,8 +197,8 @@ public class AppNotificationSettings extends SettingsPreferenceFragment {
         }
     }
 
-    private void updateDependents(boolean banned) {
-        setVisible(mBlock, !mIsSystemPackage);
+    private void updateDependents(boolean isSystemPackage, boolean banned) {
+        setVisible(mBlock, !isSystemPackage);
         if (mCategories != null) {
             setVisible(mCategories, !banned);
         }
diff --git a/src/com/android/settings/notification/ImportanceSeekBarPreference.java b/src/com/android/settings/notification/ImportanceSeekBarPreference.java
index 58892e32cd3..190a9ab0127 100644
--- a/src/com/android/settings/notification/ImportanceSeekBarPreference.java
+++ b/src/com/android/settings/notification/ImportanceSeekBarPreference.java
@@ -36,6 +36,7 @@ public class ImportanceSeekBarPreference extends SeekBarPreference implements
     private Callback mCallback;
     private TextView mSummaryTextView;
     private String mSummary;
+    private int mMinProgress;
 
     public ImportanceSeekBarPreference(Context context, AttributeSet attrs, int defStyleAttr,
             int defStyleRes) {
@@ -59,6 +60,10 @@ public class ImportanceSeekBarPreference extends SeekBarPreference implements
         mCallback = callback;
     }
 
+    public void setMinimumProgress(int minProgress) {
+        mMinProgress = minProgress;
+    }
+
     @Override
     public void onBindViewHolder(PreferenceViewHolder view) {
         super.onBindViewHolder(view);
@@ -72,8 +77,12 @@ public class ImportanceSeekBarPreference extends SeekBarPreference implements
     }
 
     @Override
-    public void onProgressChanged(SeekBar seekBar, final int progress, boolean fromTouch) {
+    public void onProgressChanged(SeekBar seekBar, int progress, boolean fromTouch) {
         super.onProgressChanged(seekBar, progress, fromTouch);
+        if (progress < mMinProgress) {
+            seekBar.setProgress(mMinProgress);
+            progress = mMinProgress;
+        }
         if (mSummaryTextView != null) {
             mSummaryTextView.setText(getProgressSummary(progress));
         }
diff --git a/src/com/android/settings/notification/NotificationBackend.java b/src/com/android/settings/notification/NotificationBackend.java
index 15f82fe02c3..d37cccaa76b 100644
--- a/src/com/android/settings/notification/NotificationBackend.java
+++ b/src/com/android/settings/notification/NotificationBackend.java
@@ -22,12 +22,14 @@ import android.app.Notification;
 import android.content.Context;
 import android.content.Intent;
 import android.content.pm.ApplicationInfo;
+import android.content.pm.PackageInfo;
 import android.content.pm.PackageManager;
 import android.content.pm.ParceledListSlice;
 import android.graphics.drawable.Drawable;
 import android.os.ServiceManager;
 import android.service.notification.NotificationListenerService;
 import android.util.Log;
+import com.android.settingslib.Utils;
 
 import java.util.List;
 
@@ -52,12 +54,19 @@ public class NotificationBackend {
         return row;
     }
 
-    public TopicRow loadTopicRow(PackageManager pm, ApplicationInfo app, Notification.Topic topic) {
+    public AppRow loadAppRow(PackageManager pm, PackageInfo app) {
+        final AppRow row = loadAppRow(pm, app.applicationInfo);
+        row.systemApp = Utils.isSystemPackage(pm, app);
+        return row;
+    }
+
+    public TopicRow loadTopicRow(PackageManager pm, PackageInfo app, Notification.Topic topic) {
         final TopicRow row = new TopicRow();
         row.pkg = app.packageName;
-        row.uid = app.uid;
+        row.uid = app.applicationInfo.uid;
         row.label = topic.getLabel();
-        row.icon = app.loadIcon(pm);
+        row.icon = app.applicationInfo.loadIcon(pm);
+        row.systemApp = Utils.isSystemPackage(pm, app);
         row.topic = topic;
         row.priority = getBypassZenMode(row.pkg, row.uid, row.topic);
         row.sensitive = getSensitive(row.pkg, row.uid, row.topic);
@@ -170,6 +179,7 @@ public class NotificationBackend {
         public Intent settingsIntent;
         public boolean banned;
         public boolean first;  // first app in section
+        public boolean systemApp;
     }
 
     public static class TopicRow extends AppRow {
diff --git a/src/com/android/settings/notification/TopicNotificationSettings.java b/src/com/android/settings/notification/TopicNotificationSettings.java
index e8586c27af6..f2cbf1a551e 100644
--- a/src/com/android/settings/notification/TopicNotificationSettings.java
+++ b/src/com/android/settings/notification/TopicNotificationSettings.java
@@ -34,6 +34,7 @@ import android.os.Bundle;
 import android.os.UserHandle;
 import android.provider.Settings;
 import android.service.notification.NotificationListenerService;
+import android.service.notification.NotificationListenerService.Ranking;
 import android.support.v14.preference.SwitchPreference;
 import android.support.v7.preference.Preference;
 import android.support.v7.preference.Preference.OnPreferenceChangeListener;
@@ -130,9 +131,11 @@ public class TopicNotificationSettings extends SettingsPreferenceFragment {
         mPriority = (SwitchPreference) findPreference(KEY_BYPASS_DND);
         mSensitive = (SwitchPreference) findPreference(KEY_SENSITIVE);
 
-        mTopicRow = mBackend.loadTopicRow(pm, info.applicationInfo, topic);
+        mTopicRow = mBackend.loadTopicRow(pm, info, topic);
 
-        mImportance.setMax(4);
+        mImportance.setMinimumProgress(
+                mTopicRow.systemApp ? Ranking.IMPORTANCE_LOW : Ranking.IMPORTANCE_NONE);
+        mImportance.setMax(Ranking.IMPORTANCE_MAX);
         // TODO: stop defaulting to 'normal' in the UI when there are mocks for this scenario.
         int importance =
                 mTopicRow.importance == NotificationListenerService.Ranking.IMPORTANCE_UNSPECIFIED