diff --git a/sanic/asgi.py b/sanic/asgi.py
index 8f379358..59d91990 100644
--- a/sanic/asgi.py
+++ b/sanic/asgi.py
@@ -281,7 +281,7 @@ class ASGIApp:
             await self.transport.send({
                 "type": "http.response.start",
                 "status": response.status,
-                "headers": response.full_headers,
+                "headers": response.processed_headers,
             })
             response_body = getattr(response, "body", None)
             if response_body:
diff --git a/sanic/headers.py b/sanic/headers.py
index 78140e83..74a797ee 100644
--- a/sanic/headers.py
+++ b/sanic/headers.py
@@ -7,6 +7,7 @@ from sanic.helpers import STATUS_CODES
 
 
 HeaderIterable = Iterable[Tuple[str, Any]]  # Values convertible to str
+HeaderBytesIterable = Iterable[Tuple[bytes, bytes]]
 Options = Dict[str, Union[int, str]]  # key=value fields in various headers
 OptionsIterable = Iterable[Tuple[str, str]]  # May contain duplicate keys
 
@@ -175,26 +176,13 @@ def parse_host(host: str) -> Tuple[Optional[str], Optional[int]]:
     return host.lower(), int(port) if port is not None else None
 
 
-def format_http1(headers: HeaderIterable) -> bytes:
-    """Convert a headers iterable into HTTP/1 header format.
-
-    - Outputs UTF-8 bytes where each header line ends with \\r\\n.
-    - Values are converted into strings if necessary.
-    """
-    return "".join(f"{name}: {val}\r\n" for name, val in headers).encode()
-
-
 def format_http1_response(
-    status: int, headers: HeaderIterable, body=b""
+    status: int, headers: HeaderBytesIterable, body=b""
 ) -> bytes:
-    """Format a full HTTP/1.1 response.
-
-    - If `body` is included, content-length must be specified in headers.
-    """
-    headerbytes = format_http1(headers)
+    """Format a full HTTP/1.1 response."""
     return b"HTTP/1.1 %d %b\r\n%b\r\n%b" % (
         status,
         STATUS_CODES.get(status, b"UNKNOWN"),
-        headerbytes,
+        b"".join(b"%b: %b\r\n" % h for h in headers),
         body,
     )
diff --git a/sanic/http.py b/sanic/http.py
index 97cdb0a8..29821b07 100644
--- a/sanic/http.py
+++ b/sanic/http.py
@@ -10,7 +10,7 @@ from sanic.exceptions import (
     ServiceUnavailable,
 )
 from sanic.headers import format_http1_response
-from sanic.helpers import has_message_body, remove_entity_headers
+from sanic.helpers import has_message_body
 from sanic.log import access_logger, logger
 
 
@@ -182,14 +182,9 @@ class Http:
             data, end_stream = res.body, True
         size = len(data)
         headers = res.headers
-        if res.content_type and "content-type" not in headers:
-            headers["content-type"] = res.content_type
         status = res.status
         if not isinstance(status, int) or status < 200:
             raise RuntimeError(f"Invalid response status {status!r}")
-        # Not Modified, Precondition Failed
-        if status in (304, 412):
-            headers = remove_entity_headers(headers)
         if not has_message_body(status):
             # Header-only response status
             self.response_func = None
@@ -227,7 +222,7 @@ class Http:
             data = b""
             self.response_func = self.head_response_ignored
         headers["connection"] = "keep-alive" if self.keep_alive else "close"
-        ret = format_http1_response(status, headers.items(), data)
+        ret = format_http1_response(status, res.processed_headers, data)
         # Send a 100-continue if expected and not Expectation Failed
         if self.expecting_continue:
             self.expecting_continue = False
diff --git a/sanic/response.py b/sanic/response.py
index da6929e6..2cc74e1e 100644
--- a/sanic/response.py
+++ b/sanic/response.py
@@ -7,8 +7,7 @@ from urllib.parse import quote_plus
 
 from sanic.compat import Header, open_async
 from sanic.cookies import CookieJar
-from sanic.headers import format_http1
-from sanic.helpers import has_message_body
+from sanic.helpers import has_message_body, remove_entity_headers
 
 
 try:
@@ -25,9 +24,6 @@ class BaseHTTPResponse:
     def _encode_body(self, data):
         return data.encode() if hasattr(data, "encode") else data
 
-    def _parse_headers(self):
-        return format_http1(self.full_headers)
-
     @property
     def cookies(self):
         if self._cookies is None:
@@ -35,14 +31,22 @@ class BaseHTTPResponse:
         return self._cookies
 
     @property
-    def full_headers(self):
-        """Obtain an encoded tuple of headers for a response to be sent."""
+    def processed_headers(self):
+        """Obtain a list of header tuples encoded in bytes for sending.
+
+        Add and remove headers based on status and content_type.
+        """
         headers = []
         cookies = {}
-        if self.content_type and not "content-type" in self.headers:
-            headers += (b"content-type", self.content_type.encode()),
+        status = self.status
+        # TODO: Make a blacklist set of header names and then filter with that
+        if status in (304, 412):  # Not Modified, Precondition Failed
+            self.headers = remove_entity_headers(self.headers)
+        if has_message_body(status):
+            if self.content_type and not "content-type" in self.headers:
+                headers += (b"content-type", self.content_type.encode()),
         for name, value in self.headers.items():
-            name = f"{name}"
+            name = f"{name}".lower()
             if name.lower() == "set-cookie":
                 cookies[value.key] = value
             else:
@@ -126,12 +130,6 @@ class HTTPResponse(BaseHTTPResponse):
         self.headers = Header(headers or {})
         self._cookies = None
 
-    @property
-    def cookies(self):
-        if self._cookies is None:
-            self._cookies = CookieJar(self.headers)
-        return self._cookies
-
 
 def empty(status=204, headers=None):
     """