diff --git a/README.md b/README.md
index 30fda6a..2b15ac8 100644
--- a/README.md
+++ b/README.md
@@ -1,7 +1,7 @@
 # good-map
 
 Transform stream for [Hapi Good](https://github.com/hapijs/good) process monitoring.
-Properties of the incoming object stream can be modified with your own mapping functions.
+Modify the incoming object stream with your own mapping functions.
 
 [![Build Status](https://travis-ci.org/frankthelen/good-map.svg?branch=master)](https://travis-ci.org/frankthelen/good-map)
 [![Coverage Status](https://coveralls.io/repos/github/frankthelen/good-map/badge.svg?branch=master)](https://coveralls.io/github/frankthelen/good-map?branch=master)
@@ -63,10 +63,11 @@ await server.start();
 
 The `good-map` transform stream can be placed anywhere in the pipeline where log values are still objects, e.g., after `Squeeze`.
 
-`GoodMap(rules, [options])` has the following parameters:
+`args` in the Good configuration for `good-map` is an array with two arguments which are passed to `GoodMap(rules, [options])`:
 
- * `rules`: An object with the following parameters:
-   - `events`: An optional list of Hapi server events, e.g., `['request']`, for filtering purposes.
-   - `tags`: An optional list of event tags, e.g., `['error']`, for filtering purposes.
-   - `map`: An object mapping log item properties (including deep properties separated by dots), e.g., `timestamp` or `error.message`, using a mapping function of the form `value => 'newValue'`, e.g., `() => '***'` or `str => str.toUpperCase()`. If a property does not exist (before), it will *not* be set. If the mapping function returns `undefined`, the property will be deleted. If the mapping function throws an error (for whatever reason), the error will be suppressed.
- * `options`: Optional configuration object that gets passed to the Node [Stream.Transform](http://nodejs.org/api/stream.html#stream_class_stream_transform) constructor. `objectMode` is always `true`.
+ * `rules`: An object with the following parameters (all optional):
+   - `events`: A list of Hapi server event types, e.g., `['request']`, for filtering purposes.
+   - `tags`: A list of event tags, e.g., `['error']`, for filtering purposes.
+   - `map`: An object that maps the log item's properties (including deep properties separated by dots), e.g., `timestamp` or `'error.message'` to a mapping function (synchronous). It has the form `(value) => 'newValue'`, e.g., `() => '***'` or `str => str.toUpperCase()`. If a property does not exist (before), it is *not* set. If the mapping function returns `undefined`, the property is deleted. If the mapping function throws an error, the error is ignored. For full flexibility, the second parameter provides access to the complete log item: `(value, item) => ...`.
+   - `observe`: Listen to the complete log item as it appears in the stream. The observer function (synchronous) has the form `(item) => { ... }`. If the observer function throws an error, the error is ignored.
+ * `options`: An optional configuration object that gets passed to the Node [Stream.Transform](http://nodejs.org/api/stream.html#stream_class_stream_transform) constructor. `objectMode` is always `true`.
diff --git a/package.json b/package.json
index cd0cd7a..d95075c 100644
--- a/package.json
+++ b/package.json
@@ -1,6 +1,6 @@
 {
   "name": "good-map",
-  "version": "1.0.0",
+  "version": "1.1.0",
   "description": "Transform stream for Hapi Good process monitoring",
   "main": "src/index.js",
   "repository": {
diff --git a/src/index.js b/src/index.js
index 4ab3702..9fd29dc 100644
--- a/src/index.js
+++ b/src/index.js
@@ -6,13 +6,17 @@ const unset = require('lodash.unset');
 class GoodMap extends Stream.Transform {
   constructor(rules = {}, options = {}) {
     super({ ...options, objectMode: true });
-    const { events = [], tags = [], map = {} } = rules;
+    const {
+      events = [], tags = [], map = {}, observe = () => {},
+    } = rules;
     this.events = events;
     this.tags = tags;
     this.map = map;
     this.props = Object.keys(map);
+    this.observe = observe;
   }
   _transform(data, enc, next) {
+    // filter
     const { event, tags = [] } = data;
     if (this.events.length && !this.events.includes(event)) {
       return next(null, data);
@@ -20,13 +24,14 @@ class GoodMap extends Stream.Transform {
     if (this.tags.length && !this.tags.reduce((acc, tag) => acc || tags.includes(tag), false)) {
       return next(null, data);
     }
+    // map properties
     this.props.forEach((prop) => {
       try {
         const value = get(data, prop);
         if (value === undefined) {
           // do nothing
         } else {
-          const newValue = this.map[prop](value);
+          const newValue = this.map[prop](value, data);
           if (newValue === undefined) {
             unset(data, prop);
           } else {
@@ -37,6 +42,13 @@ class GoodMap extends Stream.Transform {
         // ignore
       }
     });
+    // observe
+    try {
+      this.observe(data);
+    } catch (error) {
+      // ignore
+    }
+    // continue
     return next(null, data);
   }
 }
diff --git a/test/index.spec.js b/test/index.spec.js
index 7702bdb..d71a11b 100644
--- a/test/index.spec.js
+++ b/test/index.spec.js
@@ -133,4 +133,36 @@ describe('GoodMap', () => {
     expect(result.length).to.equal(3);
     expect(result[2]).to.not.have.property('timestamp');
   });
+
+  it('should provide the log item in the mapping function', async () => {
+    const collect = [];
+    const options = {
+      map: {
+        prop: (value, item) => { collect.push(item); return true; },
+      },
+    };
+    await pipe(options, testEvents);
+    expect(collect.length).to.equal(3);
+    expect(collect[0]).to.deep.equal({ ...testEvents[0], prop: true });
+    expect(collect[1]).to.deep.equal({ ...testEvents[1], prop: true });
+    expect(collect[2]).to.deep.equal({ ...testEvents[2], prop: true });
+  });
+
+  it('should call the observer function after mapping', async () => {
+    const collect = [];
+    const options = {
+      map: {
+        prop: () => true,
+      },
+      observe: (item) => {
+        item.bla = true; // eslint-disable-line no-param-reassign
+        collect.push(item);
+      },
+    };
+    await pipe(options, testEvents);
+    expect(collect.length).to.equal(3);
+    expect(collect[0]).to.deep.equal({ ...testEvents[0], prop: true, bla: true });
+    expect(collect[1]).to.deep.equal({ ...testEvents[1], prop: true, bla: true });
+    expect(collect[2]).to.deep.equal({ ...testEvents[2], prop: true, bla: true });
+  });
 });