diff --git a/learned_optimization/research/univ_nfn/learned_opt/learned_opts.py b/learned_optimization/research/univ_nfn/learned_opt/learned_opts.py
index d3ffeab..12649df 100644
--- a/learned_optimization/research/univ_nfn/learned_opt/learned_opts.py
+++ b/learned_optimization/research/univ_nfn/learned_opt/learned_opts.py
@@ -35,7 +35,6 @@
 from learned_optimization.learned_optimizers import base as lopt_base
 from learned_optimization.learned_optimizers import common
 from learned_optimization.optimizers import base as opt_base
-from learned_optimization.research.univ_nfn.nfn import ff_layers as nf_layers
 from learned_optimization.research.univ_nfn.nfn import universal_layers
 from learned_optimization.research.univ_nfn.nfn import utils as nfu
 
@@ -89,42 +88,6 @@ class SimpleOptState(flax.struct.PyTreeNode):
   state: Any
 
 
-def flax_to_hk(input_dict):
-  """Maps flax parameter structure to haiku parameter structure.
-
-  Example:
-  >>> input_dict = {
-  ...     'params': {
-  ...         'Dense_0': {'kernel': W0, 'bias': b0},
-  ...         'Dense_1': {'kernel': W1, 'bias': b1}
-  ...     }
-  ... }
-  >>> transform_dict(input_dict)
-  {'mlp/~/linear_0': {'w': W0, 'b': b0}, 'mlp/~/linear_1': {'w': W1, 'b': b1}}
-  """
-  params = input_dict.get('params', {})
-  output_dict = {}
-  for i, (_, layer_data) in enumerate(params.items()):
-    # Constructing new key and sub-dictionary format
-    new_key = f'mlp/~/linear_{i}'
-    new_data = {'w': layer_data['kernel'], 'b': layer_data['bias']}
-    output_dict[new_key] = new_data
-  return output_dict
-
-
-def hk_to_flax(input_dict):
-  """Maps haiku parameter structure to flax parameter structure."""
-  output_dict = {'params': {}}
-
-  for key, layer_data in input_dict.items():
-    # Extracting the layer number from the key
-    layer_num = key.split('_')[-1]  # Get the part after the last '_'
-    original_layer_name = f'Dense_{layer_num}'
-    original_data = {'kernel': layer_data['w'], 'bias': layer_data['b']}
-    output_dict['params'][original_layer_name] = original_data
-  return output_dict
-
-
 def make_hk_perm_spec(mlp_params):
   """Produces perm spec for a haiku mlp."""
   perm_spec = {}
@@ -153,17 +116,57 @@ def make_hk_cnn_perm_spec(mlp_params):
   return perm_spec
 
 
+def build_init_fn(scale, shape):
+  return lambda rng, _shape: scale * jax.random.normal(rng, shape)
+
+
+class PosEmbConv(nn.Module):
+  """Add learned position embeddings for spatial dims of conv input."""
+
+  @nn.compact
+  def __call__(self, inp_features):
+    features, tree_def = jtu.tree_flatten(inp_features)
+    out_features = []
+    for i, val in enumerate(features):
+      if len(val.shape) == 5:  # conv2d filter: HxWxC1xC2xC
+        shape = (val.shape[0], val.shape[1], 1, 1, val.shape[-1])
+        scale = 0.17  # roughly 1 / sqrt(32), to match scale of kernel at init
+        pos_emb = self.param(f'pos_emb_{i}', build_init_fn(scale, shape), shape)
+        out_features.append(pos_emb + val)
+      else:
+        out_features.append(val)
+    out_features = jtu.tree_unflatten(tree_def, out_features)
+    return out_features
+
+
+def make_hk_irnn_perm_spec(mlp_params):
+  """Tested on RNNLM_lm1bbytes_Patch32_IRNN128_Embed64."""
+  # -1: vocab, 0: embed, 1: hidden
+  del mlp_params
+  perm_spec = {
+      'embed': {'embeddings': (-1, 0)},
+      'irnn/linear': {'b': (1,), 'w': (0, 1)},
+      'irnn/linear_1': {'b': (1,), 'w': (1, 1)},
+      'linear': {'b': (-1,), 'w': (1, -1)},
+      '~': {'initial_state_0': (-2, 1)},
+  }
+  return perm_spec
+
+
 class MLPForOpt(nn.Module):
   """MLP for learned opt."""
 
   hidden_channels: int
   out_channels: int
   num_layers: int
+  pos_emb: bool = False
 
   def setup(self):
     layers = []
-    for _ in range(self.num_layers - 1):
+    for i in range(self.num_layers - 1):
       layers.append(nn.Dense(self.hidden_channels))
+      if i == 0 and self.pos_emb:
+        layers.append(PosEmbConv())
       layers.append(jax.nn.relu)
     layers.append(nn.Dense(self.out_channels))
     self.mod = nn.Sequential(layers)
@@ -173,38 +176,6 @@ def __call__(self, inp_features):
     return jtu.tree_map(self.mod, inp_features)
 
 
-class NFNForOpt(nn.Module):
-  """NFN for learned opt."""
-
-  in_channels: int
-  hidden_channels: int
-  out_channels: int
-  num_layers: int
-  pos_enc: bool = True
-  hnet: bool = False
-
-  def setup(self):
-    assert not (self.hnet and self.pos_enc), 'Only one of these can be on.'
-    in_channels, hidden_channels = self.in_channels, self.hidden_channels
-    layer_cls = lambda *args, **kwargs: nf_layers.NFLinearMlp(
-        *args, **kwargs, pe_enabled=self.pos_enc
-    )
-    if self.hnet:
-      layer_cls = nf_layers.NFLinearMlpHNet
-    layers = [layer_cls(hidden_channels, in_channels), nf_layers.nf_relu]
-    for _ in range(self.num_layers - 2):
-      layers.append(layer_cls(hidden_channels, hidden_channels))
-      layers.append(nf_layers.nf_relu)
-    layers.append(layer_cls(self.out_channels, hidden_channels))
-    self.mod = nn.Sequential(layers)
-
-  def __call__(self, inp_features):
-    # add batch dimension for nf layers
-    inp_features = nfu.tree_expand_dims(inp_features, 0)
-    out = flax_to_hk(self.mod(hk_to_flax(inp_features))[0])
-    return nfu.tree_squeeze(out, 0)
-
-
 class UnivNFNForOpt(nn.Module):
   """Univeral NFN for learned opt."""
 
@@ -214,6 +185,7 @@ class UnivNFNForOpt(nn.Module):
   num_layers: int
   perm_spec: Any
   ptwise_init: bool = False
+  pos_emb: bool = False
 
   def setup(self):
     in_channels, hidden_channels = self.in_channels, self.hidden_channels
@@ -224,10 +196,10 @@ def make_layer(out_chan, in_chan):
       else:
         return universal_layers.NFLinear(out_chan, in_chan, w_init='lecun')
 
-    layers = [
-        make_layer(hidden_channels, in_channels),
-        universal_layers.nf_relu,
-    ]
+    layers = [make_layer(hidden_channels, in_channels)]
+    if self.pos_emb:
+      layers.append(PosEmbConv())
+    layers.append(universal_layers.nf_relu)
     for _ in range(self.num_layers - 1):
       layers.append(make_layer(hidden_channels, hidden_channels))
       layers.append(universal_layers.nf_relu)
@@ -434,10 +406,14 @@ def norm_second_moment(p):
 class ResidualOptNFN(ResidualOpt):
   """NFN learning a residual on base optimizer."""
 
-  def __init__(self, task, step_mult=0.1, out_mult=1e-4, ptwise_init=False):
+  def __init__(
+      self, task, step_mult=0.1, out_mult=1e-4, ptwise_init=False, pos_emb=False
+  ):
     example_params = task.init(jax.random.PRNGKey(0))
     if 'conv2_d' in example_params:
       perm_spec = make_hk_cnn_perm_spec(example_params)
+    elif 'irnn/linear' in example_params:
+      perm_spec = make_hk_irnn_perm_spec(example_params)
     else:
       perm_spec = make_hk_perm_spec(example_params)
     network = UnivNFNForOpt(
@@ -447,6 +423,7 @@ def __init__(self, task, step_mult=0.1, out_mult=1e-4, ptwise_init=False):
         num_layers=4,
         perm_spec=perm_spec,
         ptwise_init=ptwise_init,
+        pos_emb=pos_emb,
     )
     super().__init__(
         network, example_params, step_mult=step_mult, out_mult=out_mult
@@ -456,9 +433,11 @@ def __init__(self, task, step_mult=0.1, out_mult=1e-4, ptwise_init=False):
 @gin.configurable
 class ResidualOptMLP(ResidualOpt):
 
-  def __init__(self, task, step_mult=0.1, out_mult=1e-4):
+  def __init__(self, task, step_mult=0.1, out_mult=1e-4, pos_emb=False):
     example_params = task.init(jax.random.PRNGKey(0))
-    network = MLPForOpt(hidden_channels=32, out_channels=1, num_layers=4)
+    network = MLPForOpt(
+        hidden_channels=32, out_channels=1, num_layers=4, pos_emb=pos_emb
+    )
     super().__init__(
         network, example_params, step_mult=step_mult, out_mult=out_mult
     )
diff --git a/learned_optimization/research/univ_nfn/nfn/siren.py b/learned_optimization/research/univ_nfn/nfn/siren.py
index 6e93e57..cdb8d01 100644
--- a/learned_optimization/research/univ_nfn/nfn/siren.py
+++ b/learned_optimization/research/univ_nfn/nfn/siren.py
@@ -19,7 +19,6 @@
 from typing import Any, Callable, Optional, Tuple
 
 from flax import linen as nn
-from flax import nn as fnn
 import jax
 from jax import lax
 import jax.numpy as jnp
@@ -113,7 +112,7 @@ class ModulatedLayer(nn.Module):
   features: int = 32
   is_first: bool = False
   synthesis_act: Callable = jnp.sin
-  modulator_act: Callable = fnn.relu
+  modulator_act: Callable = nn.relu
   precision: Any = None
   dtype: Any = jnp.float32
   w0_first_layer: float = 30.0
@@ -196,7 +195,7 @@ class ModulatedSiren(nn.Module):
   output_dim: int = 3
   num_layers: int = 5
   synthesis_act: Callable = jnp.sin
-  modulator_act: Callable = fnn.relu
+  modulator_act: Callable = nn.relu
   final_activation: Callable = lambda x: x
   w0_first_layer: float = 30.0
   dtype: Any = jnp.float32